MDCAT 2023 Physics

MDCAT 2023 Physics Past Paper MCQs with Answers

180 Physics MCQs that appeared in MDCAT 2023, arranged unit by unit in syllabus order. Tap “Show answer” under any question for the correct option and a short solution.

Force and Motion

1.Which of the following is the correct definition of variable velocity? (MDCAT 2023)

  1. unequal distances are covered in equal intervals of time
  2. equal displacements are made in unequal intervals of time
  3. unequal displacements are made in equal intervals of time
  4. equal displacements are made in equal intervals of time
Show answer

Correct answer: (c) unequal displacements are made in equal intervals of time

Velocity is displacement per unit time, so it varies when the displacement in equal times is unequal.

2.A man is in a car that is moving with a uniform velocity. His velocity with respect to the car is: (MDCAT 2023)

  1. $10\ \mathrm{m\,s^{-1}}$
  2. $36\ \mathrm{m\,s^{-1}}$
  3. zero
  4. infinite
Show answer

Correct answer: (c) zero

He does not move relative to the car, so his velocity in the frame of the car is zero.

3.Two car traveling on straight road in opposite direction with speed 70 kmh-1 and 60 kmh-1, their relative velocity will be: (SZABMU MDCAT 2023)

  1. 10 kmh-1
  2. 130 kmh-1
  3. 65 kmh-1
  4. 5 kmh-1
Show answer

Correct answer: (b) 130 kmh-1

Moving towards each other, the speeds add: $70+60$ is $130\,\mathrm{km\,h^{-1}}$.

4.A man is in a car that is moving with the velocity of 36km/hr.His speed with respect to the car (UHS MDCAT 2023)

  1. 10m/s
  2. 36m/s
  3. Zero
  4. Infinite
Show answer

Correct answer: (c) Zero

He moves with the car, so relative to it his speed is zero.

5.In a displacement-time graph, if the slope is constant then the velocity is: (MDCAT 2023)

  1. variable
  2. constant
  3. may be variable or constant
  4. infinite
Show answer

Correct answer: (b) constant

The slope of a displacement-time graph is the velocity, so a constant slope is a constant velocity.

6.The velocity-time plot for a moving particle is a straight line. This means: (MDCAT 2023)

  1. the particle has a constant acceleration
  2. the particle has never turned around
  3. the particle has zero displacement
  4. the data are insufficient
Show answer

Correct answer: (a) the particle has a constant acceleration

The slope of a velocity-time graph is the acceleration, and a straight line has a constant slope.

7.What is the shape of velocity-time graph for constant acceleration? (UHS MDCAT 2023)

  1. Parabola line
  2. Straight line
  3. Incline curve
  4. Decline curve
Show answer

Correct answer: (b) Straight line

Constant acceleration means a constant slope, so the graph is a straight line.

8.The gradient of velocity time is equal to: (SZABMU MDCAT 2023)

  1. Distance
  2. Force
  3. Acceleration
  4. Speed
Show answer

Correct answer: (c) Acceleration

The slope of a velocity time graph is the acceleration.

9.Slope of distance time graph can never be: (SZABMU MDCAT 2023)

  1. Positive
  2. Negative
  3. Constant
  4. Zero
Show answer

Correct answer: (b) Negative

Distance can only grow, so the slope of the graph is never below zero.

10.The slope of a displacement-time graph is equal to: (NUMS MDCAT 2023)

  1. Velocity
  2. Displacement
  3. Acceleration
  4. Distance
Show answer

Correct answer: (a) Velocity

The slope of a displacement time graph is the velocity.

11.The velocity-time plot for a moving particle shows a straight line. This means: (UHS MDCAT 2023)

  1. The particle has a constant acceleration
  2. The particle has never turned around
  3. The particle has zero displacement
  4. The data in insufficient
Show answer

Correct answer: (a) The particle has a constant acceleration

A straight velocity time line has a constant slope, that is a constant acceleration.

12.In the displacement-time graph, if the slope is constant then the velocity is (UHS MDCAT 2023)

  1. Variable
  2. Constant
  3. May be variable or constant
  4. Infinite
Show answer

Correct answer: (b) Constant

The slope of a displacement time graph is the velocity, so a constant slope is a constant velocity.

13.If the car is slowing down along negative x axis then acceleration will be along: (NUMS MDCAT 2023)

  1. Positive x Axis
  2. Negative x Axis
  3. Positive y Axis
  4. Negative y Axis
Show answer

Correct answer: (a) Positive x Axis

Slowing down means the acceleration points against the motion, so along the positive axis.

14.At highest point in a projectile motion, the velocity will be: (SZABMU MDCAT 2023)

  1. Vx = 0 Vy = 0
  2. Vx = 0 Vy = constant
  3. Vx = constant Vy = constant
  4. Vx = constant Vy = 0
Show answer

Correct answer: (d) Vx = constant Vy = 0

Gravity empties the vertical component at the top and leaves the horizontal one untouched.

15.At what point during the motion of projectile its vertical component of velocity is zero? (NUMS MDCAT 2023)

  1. Point of projection
  2. Landing point
  3. Highest point
  4. Just before landing
Show answer

Correct answer: (c) Highest point

The vertical component is spent at the highest point of the path.

16.At what pair of angles for a projectile, the ranges are equal? (SZABMU MDCAT 2023)

  1. 20O, 60O
  2. 60O, 30O
  3. 40O, 60O
  4. 25O, 55O
Show answer

Correct answer: (b) 60O, 30O

Two angles adding to $90^{\circ}$ give the same range.

17.The angle of projection of a projectile for which its maximum height and horizontal range are equal is: (SZABMU MDCAT 2023)

  1. 86O
  2. 46 O
  3. 66 O
  4. 76 O
Show answer

Correct answer: (d) 76 O

$H=R$ gives $\tan\theta=4$, so the angle is about $76^{\circ}$.

18.Range of a projectile on a horizontal plane is same for the following pair of angle: (NUMS MDCAT 2023)

  1. 15 & 30
  2. 60 & 20
  3. 75 & 15
  4. 50 & 25
Show answer

Correct answer: (c) 75 & 15

Two angles adding to $90^{\circ}$ give the same range, and $75+15$ is the only such pair.

19.A fireman wants to slide down a rope. The breaking load of the rope is 3/4 th of the weight of the man. With what acceleration should the fire man slide down? ( Acceleration due to gravity is 'g') (UHS MDCAT 2023)

  1. g
  2. g/4
  3. 3g/4
  4. 0
Show answer

Correct answer: (b) g/4

The rope will bear only $3mg/4$, so the least downward force is $mg/4$ and the acceleration $g/4$.

20.If two equal masses are in motion with the same individual speeds, we can conclude that: (MDCAT 2023)

  1. their momenta are the same
  2. their momenta can be different from each other
  3. their kinetic energies are different from each other
  4. their total energies are different
Show answer

Correct answer: (b) their momenta can be different from each other

Momentum is a vector, so equal masses at equal speeds in different directions have different momenta.

21.Two balls collide each other, it has been observed that the collision is elastic. Which statement is advocates the observation? (SZABMU MDCAT 2023)

  1. K.E before collision = K.E after collision
  2. Momentum before collision = Momentum after collision
  3. K.E before collision ≠ K.E after collision
  4. Momentum before collision ≠ Momentum after collision
Show answer

Correct answer: (a) K.E before collision = K.E after collision

Momentum is conserved in every collision; it is the kinetic energy that marks an elastic one.

22.Two bodies having same mass undergo elastic collision then their velocities after collision will be: (SZABMU MDCAT 2023)

  1. v1' = 0 v2' = v1
  2. v1' = v2 v2' = 0
  3. v1' = v1 v2' = v2
  4. v1' = v2 v2' = v1
Show answer

Correct answer: (d) v1' = v2 v2' = v1

Equal masses in a head-on elastic collision simply exchange velocities.

23.In perfectly elastic collision: (NUMS MDCAT 2023)

  1. Only momentum is conserved
  2. Only total energy is conserved
  3. Only kinetic energy is conserved
  4. Momentum, kinetic energy and total energy, all are conserved
Show answer

Correct answer: (d) Momentum, kinetic energy and total energy, all are conserved

Momentum, kinetic energy and total energy are all conserved in a perfectly elastic collision.

Work and Energy

24.The work done by a variable force can be found by dividing the: (MDCAT 2023)

  1. force into small intervals
  2. displacement into small intervals
  3. both force and displacement into small intervals
  4. displacement into intervals at different angles
Show answer

Correct answer: (b) displacement into small intervals

Over a small enough displacement the force is effectively constant, so $W=\sum F\Delta d$ is the area under the force-displacement graph.

25.Work done will be negative if the angle between force and displacement is: (SZABMU MDCAT 2023)

  1. 0 O
  2. 45 O
  3. 60 O
  4. 180 O
Show answer

Correct answer: (d) 180 O

At $180^{\circ}$ the cosine is $-1$, so the work is negative.

26.The area under force-displacement graph gives: (NUMS MDCAT 2023)

  1. Displacement
  2. Power
  3. Work
  4. Acceleration
Show answer

Correct answer: (c) Work

Force times displacement is work, and that is the area under the graph.

27.An 8.0 kg box slides along a horizontal frictionless floor at $3\ \mathrm{m\,s^{-1}}$ and meets a light spring that compresses 12 cm before the box stops. Calculate the retarding force of the spring. (MDCAT 2023)

  1. 3 N
  2. 30 N
  3. 300 N
  4. 3000 N
Show answer

Correct answer: (c) 300 N

$\tfrac{1}{2}mv^2=\tfrac{1}{2}(8)(3)^2=36$ J, and $F=W/d=36/0.12=300$ N.

28.Two bodies with kinetic energies in the ratio 4 : 1 are moving with equal linear momentum. The ratio of their masses is: (MDCAT 2023)

  1. 1 : 4
  2. 4 : 1
  3. 1 : 2
  4. 2 : 1
Show answer

Correct answer: (a) 1 : 4

With $p$ equal, $E_k=p^2/2m$, so the kinetic energy is inversely proportional to the mass.

29.A particle of mass m at rest is acted upon by a force P for time t. Its kinetic energy after time t is: (UHS MDCAT 2023)

  1. (P^2 t^2)/m
  2. (P^2 t^2)/2m
  3. (P^2 t^2)/3m
  4. (P^2 t^2)/4m
Show answer

Correct answer: (b) (P^2 t^2)/2m

The impulse $Pt$ is the momentum gained, and $K=p^2/2m$ gives $P^2t^2/2m$.

30.The unit of kinetic energy is same as that of: (SZABMU MDCAT 2023)

  1. Work
  2. Power / Time
  3. Time / Power
  4. Work / Time
Show answer

Correct answer: (a) Work

Kinetic energy is measured in joules, the same unit as work.

31.A car of mass 800 Kg accelerates from 20m-1 to 30ms-1, the increase in K.E is: (SZABMU MDCAT 2023)

  1. 2 J
  2. 200 KJ
  3. 200 J
  4. 2 KJ
Show answer

Correct answer: (b) 200 KJ

$\tfrac12\times800\times(30^2-20^2)$ is $200\,\mathrm{kJ}$.

32.A body of mass 'm' is moving with velocity 'v'. After a short interval of time its velocity becomes double. How many times its K.E will increase or decrease? (NUMS MDCAT 2023)

  1. 2 time increased
  2. 2 time decreased
  3. 4 time increased
  4. 4 time decreased
Show answer

Correct answer: (c) 4 time increased

$K=\tfrac12mv^2$ goes as the square of the speed, so doubling it gives four times the energy.

33.An 8.0-kg box slides along a horizontal frictionless floor at 3 m/s and collides with a relatively massless spring that compresses 12 cm before the box comes to a rest. Calculate the retarding force of the spring. (UHS MDCAT 2023)

  1. 3N
  2. 30N
  3. 300N
  4. 3000N
Show answer

Correct answer: (c) 300N

The kinetic energy $\tfrac12\times8\times3^2=36\,\mathrm{J}$ is absorbed over $0.12\,\mathrm{m}$, so the force is $300\,\mathrm{N}$.

34.A fisherman lifts a fish of mass 250 g from rest through a vertical height of 1.8 m. The fish gains a speed of $1.1\ \mathrm{m\,s^{-1}}$. What is the energy gained by the fish? (MDCAT 2023)

  1. 0.15 J
  2. 4.3 J
  3. 4.4 J
  4. 4.6 J
Show answer

Correct answer: (d) 4.6 J

$mgh+\tfrac{1}{2}mv^2=0.25(9.8)(1.8)+\tfrac{1}{2}(0.25)(1.1)^2=4.41+0.15\approx4.6$ J.

35.Ignoring details associated with friction, extra forces exerted by arm and leg muscles, and other factors, we can consider a pole vault as the conversion of an athlete's running kinetic energy to gravitational potential energy. If an athlete is to lift his body 5 m during a vault, what speed must he have when he plants his pole? (UHS MDCAT 2023)

  1. 5 m/s
  2. 10 m/s
  3. 15 m/s
  4. 20 m/s
Show answer

Correct answer: (b) 10 m/s

$\tfrac12mv^2=mgh$ gives $v=\sqrt{2\times10\times5}$, about $10\,\mathrm{m\,s^{-1}}$.

36.Kilowatt hour is a unit of: (SZABMU MDCAT 2023)

  1. Energy
  2. Energy x time
  3. Power
  4. (power)(energy)
Show answer

Correct answer: (a) Energy

A kilowatt hour is power times time, that is energy.

37.The unit of power in British engineering system is: (SZABMU MDCAT 2023)

  1. Horse power
  2. Watt
  3. Js-1
  4. Js
Show answer

Correct answer: (a) Horse power

The British engineering unit of power is the horsepower.

38.1 Nms-1 = : (SZABMU MDCAT 2023)

  1. 1 Kilo watt hour
  2. 1 J.s
  3. 1 watt
  4. 1 J.s-2
Show answer

Correct answer: (c) 1 watt

A newton metre per second is a joule per second, that is a watt.

39.1 kWh = (NUMS MDCAT 2023)

  1. 0.36 × 106 J
  2. 36 × 105 J
  3. 3.6 × 106 J
  4. 0.036 × 105 J
Show answer

Correct answer: (c) 3.6 × 106 J

A kilowatt for an hour is $1000\times3600$, that is $3.6\times10^6\,\mathrm{J}$.

40.Power is dot product of: (NUMS MDCAT 2023)

  1. Force and displacement
  2. Force and velocity
  3. Force and time
  4. Work and time
Show answer

Correct answer: (b) Force and velocity

Power is the scalar product of force and velocity.

41.For an ideal gas equation PV= nRT, the dimensions of Real Gas Constant R are: (UHS MDCAT 2023)

  1. [M1 L2 T-2 K-1]
  2. [M1 L-3 T-1 K-1]
  3. [M1 L-2 T-1 K-1]
  4. [M1 L-3 T-2 K-1]
Show answer

Correct answer: (a) [M1 L2 T-2 K-1]

$R=PV/nT$ is energy per mole per kelvin, that is $[\mathrm{M\,L^2\,T^{-2}\,K^{-1}}]$.

42.In inter-conversion of energy, the work done against the friction is: (SZABMU MDCAT 2023)

  1. f + h
  2. f - h
  3. fh
  4. f / h
Show answer

Correct answer: (c) fh

Work is force times distance, so the work against a friction $f$ over a distance $h$ is $fh$.

Rotational and Circular Motion

43.One degree is equal to: (MDCAT 2023)

  1. $\pi/90$ radians
  2. $\pi/180$ radians
  3. $\pi/270$ radians
  4. $\pi/360$ radians
Show answer

Correct answer: (b) $\pi/180$ radians

A half turn is $\pi$ radians and $180^\circ$, so $1^\circ=\pi/180$ radians.

44.One radian is analogous to: (MDCAT 2023)

  1. $57.3^\circ$
  2. $57.3$ radians
  3. $1^\circ$
  4. $180^\circ$
Show answer

Correct answer: (a) $57.3^\circ$

$1\ \mathrm{rad}=180^\circ/\pi=57.3^\circ$.

45.The number of revolutions in 3π radians is: (UHS MDCAT 2023)

  1. 1/60
  2. 3/2
  3. 2
  4. 6
Show answer

Correct answer: (b) 3/2

One revolution is $2\pi$ radians, so $3\pi$ is one and a half.

46.How many radians are in one degree? (SZABMU MDCAT 2023)

  1. 0.0174 rad
  2. 0.174 rad
  3. 1.745 rad
  4. 0.00174 rad
Show answer

Correct answer: (a) 0.0174 rad

$\pi/180$ is about $0.0174$ radians.

47.The relation between radian and degree is: (NUMS MDCAT 2023)

  1. 1 rad = 57.3°
  2. 1° = 57.3 rad
  3. 1 rad = 1°
  4. 1° = π rad
Show answer

Correct answer: (a) 1 rad = 57.3°

One radian is $180/\pi$ degrees, about $57.3^{\circ}$.

48.If a flywheel is rotating at 3.0 rad/s, the time it takes to complete one revolution is about (UHS MDCAT 2023)

  1. 0.67 s
  2. 1.0 s
  3. 1.3 s
  4. 2.1 s
Show answer

Correct answer: (d) 2.1 s

$T=2\pi/\omega=2\pi/3$, about $2.1\,\mathrm{s}$.

49.Which one of the following is the angular velocity of an electric motor if it rotates at 400 rpm? (SZABMU MDCAT 2023)

  1. 51.2 rad/s
  2. 41.9 rad/s
  3. 45.2 rad/s
  4. 38.5 rad/s
Show answer

Correct answer: (b) 41.9 rad/s

$400\times2\pi/60$ gives about $41.9\,\mathrm{rad\,s^{-1}}$.

50.Which one of the following is angular speed in radian per hour for daily rotation of our earth? (SZABMU MDCAT 2023)

  1. 2 π
  2. 4 π
  3. π /6
  4. π /12
Show answer

Correct answer: (d) π /12

$2\pi$ radians in $24$ hours is $\pi/12$ radians an hour.

51.An electric motor turns at 400 revolutions per minute. Its angular velocity in rad/s will be: (NUMS MDCAT 2023)

  1. 20π/3
  2. 30π/3
  3. 40π/3
  4. 30π/4
Show answer

Correct answer: (c) 40π/3

$400\times2\pi/60$ is $40\pi/3\,\mathrm{rad\,s^{-1}}$.

52.If a particle is moving with uniform circular motion, then: (MDCAT 2023)

  1. velocity and acceleration are antiparallel
  2. velocity and acceleration are parallel
  3. velocity and acceleration are perpendicular to each other
  4. the acceleration is zero
Show answer

Correct answer: (c) velocity and acceleration are perpendicular to each other

The speed does not change, so the acceleration is wholly centripetal and at right angles to the velocity.

53.On which car is a centripetal force acting? (MDCAT 2023)

  1. a car moving on a straight horizontal road
  2. a car moving at constant speed around a bend
  3. a car moving uphill at a constant velocity
  4. a car that is stationary
Show answer

Correct answer: (b) a car moving at constant speed around a bend

Only the car going round a bend has a curved path, and the force towards the centre of that curve is the centripetal force.

54.Which one provides centripetal force in a circular motion of a body? (SZABMU MDCAT 2023)

  1. Vertical component of weight
  2. Horizontal component of weight
  3. Weight of the body
  4. Force of friction
Show answer

Correct answer: (d) Force of friction

For a car on a level bend the friction of the tyres is the only inward force.

55.The tension is string at top of vertical circle is: (SZABMU MDCAT 2023)

  1. Zero
  2. mg
  3. 2mg
  4. 3mg
Show answer

Correct answer: (a) Zero

At the least speed that keeps the string taut, gravity alone supplies the centripetal force and the tension is zero.

56.The centripetal force in terms of angular velocity is given by: (SZABMU MDCAT 2023)

  1. F c = m r ω
  2. F c = m r ω^2
  3. F c = m r α^2
  4. F c = m r α
Show answer

Correct answer: (b) F c = m r ω^2

With $v=r\omega$, $mv^2/r$ becomes $mr\omega^2$.

57.In case of centripetal force the value of instantaneous acceleration is given by: (NUMS MDCAT 2023)

  1. ac = v/r
  2. ac = v2/r
  3. ac = vr
  4. ac = v2r
Show answer

Correct answer: (b) ac = v2/r

The centripetal acceleration is $v^2/r$, directed to the centre.

58.The centripetal force formula is: (NUMS MDCAT 2023)

  1. Fc = mω2
  2. Fc = mrω
  3. Fc = mrω2
  4. Fc = mr2ω
Show answer

Correct answer: (c) Fc = mrω2

With $v=r\omega$, $mv^2/r$ becomes $mr\omega^2$.

59.On which car there is resultant force? (UHS MDCAT 2023)

  1. Car moving on a straight horizontal road
  2. Car moving at constant speed around a bend
  3. Car moving uphill at a constant velocity
  4. Car that is stationary
Show answer

Correct answer: (b) Car moving at constant speed around a bend

A car on a bend is changing direction, so there is a resultant force towards the centre.

Waves

60.The mechanical waves are not generated by: (UHS MDCAT 2023)

  1. Electric and magnetic fields
  2. Coil of springs
  3. Ropes
  4. Water
Show answer

Correct answer: (a) Electric and magnetic fields

Electric and magnetic fields make electromagnetic waves, which need no medium at all.

61.Continuous, regular and rhythmic disturbance in a medium resulting periodic vibration of a source causes________in the medium: (SZABMU MDCAT 2023)

  1. Complex waves
  2. Stationary waves
  3. Electromagnetic waves
  4. Periodic waves
Show answer

Correct answer: (d) Periodic waves

A regular repeated disturbance sets up periodic waves.

62.An observer standing near the shore observes 54 waves per minute. If the wavelength of the water wave is 2 m, the speed of the water wave is: (MDCAT 2023)

  1. $540\ \mathrm{m\,s^{-1}}$
  2. $9\ \mathrm{m\,s^{-1}}$
  3. $5.4\ \mathrm{m\,s^{-1}}$
  4. none of these
Show answer

Correct answer: (d) none of these

$f=54/60=0.9$ Hz and $v=f\lambda=0.9\times2=1.8\ \mathrm{m\,s^{-1}}$, which is none of the first three.

63.Wave trough refers to the: (MDCAT 2023)

  1. wavelength
  2. wave speed
  3. highest point of the wave
  4. lowest point of the wave
Show answer

Correct answer: (d) lowest point of the wave

The trough is the lowest point of a transverse wave, as the crest is the highest.

64.When a wave goes from one medium to another, there is no change in the: (MDCAT 2023)

  1. frequency
  2. amplitude
  3. wavelength
  4. velocity
Show answer

Correct answer: (a) frequency

The source sets the frequency, so it is unchanged; the speed and hence the wavelength change with the medium.

65.Which of the following increase by increasing amplitude? (UHS MDCAT 2023)

  1. Wavelength
  2. Frequently
  3. Zero
  4. Loudness
Show answer

Correct answer: (d) Loudness

Loudness follows the energy of the wave, which goes as the square of the amplitude.

66.The shortest distance between any two points in phase on a wave is called: (UHS MDCAT 2023)

  1. Displacement
  2. Amplitude
  3. Wavelength
  4. Frequency
Show answer

Correct answer: (c) Wavelength

The shortest distance between two points in the same phase is the wavelength.

67.Wavelength of wave is defined as: (SZABMU MDCAT 2023)

  1. Distance between two consecutive crests
  2. Distance between two alternate crest
  3. Distance between two alternate trough
  4. Distance between two crest and two trough
Show answer

Correct answer: (a) Distance between two consecutive crests

One wavelength is the distance from one crest to the next.

68.Maximum displacement of particles form it mean position is called: (SZABMU MDCAT 2023)

  1. Frequency
  2. Amplitude
  3. Wavelength
  4. Crest
Show answer

Correct answer: (b) Amplitude

The greatest displacement from the mean position is the amplitude.

69.The ultrasonic waves have frequency higher than: (SZABMU MDCAT 2023)

  1. 20 Hz
  2. 20 KHz
  3. 200 Hz
  4. 2000 KHz
Show answer

Correct answer: (b) 20 KHz

Ultrasonic means above the upper limit of hearing, about $20\,\mathrm{kHz}$.

70.The maximum displacement of particles of a medium, on either side of the mean position of a wave, is called: (NUMS MDCAT 2023)

  1. Wavelength
  2. Frequency
  3. Amplitude
  4. Crest
Show answer

Correct answer: (c) Amplitude

That greatest displacement is the amplitude.

71.When a wave goes from one medium to another, there is a no change in the: (UHS MDCAT 2023)

  1. Frequency
  2. Amplitude
  3. Wavelength
  4. Velocity
Show answer

Correct answer: (a) Frequency

The source sets the frequency, so it is unchanged; the speed and wavelength alter together.

72.An observer standing near the sea shore observes 54 waves per minute. If the wavelength of the water wave is 10m then the velocity of water wave is: (UHS MDCAT 2023)

  1. 540 m/s
  2. 9 m/s
  3. 5.4 m/s
  4. None
Show answer

Correct answer: (b) 9 m/s

Fifty-four waves a minute is $0.9\,\mathrm{Hz}$, and $v=f\lambda=0.9\times10$ is $9\,\mathrm{m\,s^{-1}}$.

73.If transverse waves are passing through a medium, then the particles of the medium: (MDCAT 2023)

  1. remain stationary
  2. move away with the wave
  3. move towards the source
  4. move in simple harmonic motion
Show answer

Correct answer: (d) move in simple harmonic motion

Each particle oscillates about its own mean position at right angles to the direction of travel.

74.If transverse waves are passing through medium, then particle of medium: (UHS MDCAT 2023)

  1. Remain stationary
  2. Move away
  3. Move toward
  4. Move in Simple Harmonic Motion
Show answer

Correct answer: (d) Move in Simple Harmonic Motion

Each particle of the medium oscillates about its mean position in simple harmonic motion.

75.The speed of sound in an ideal gas depends upon its: (MDCAT 2023)

  1. temperature
  2. frequency
  3. amplitude
  4. wavelength
Show answer

Correct answer: (a) temperature

$v\propto\sqrt{T}$; the frequency, amplitude and wavelength of the sound do not change it.

76.Which of the following factor does not affect the speed of sound in air? (SZABMU MDCAT 2023)

  1. Pressure
  2. Density
  3. Temperature
  4. Medium
Show answer

Correct answer: (a) Pressure

Raising the pressure raises the density in the same proportion, so $\sqrt{P/\rho}$ is unchanged.

77.The increase in the speed of sound for each degree rise above 0o C is: (SZABMU MDCAT 2023)

  1. 0.61 m/s
  2. 0.51 m/s
  3. 0.41 m/s
  4. 0.31 m/s
Show answer

Correct answer: (a) 0.61 m/s

Sound gains about $0.61\,\mathrm{m\,s^{-1}}$ for each degree above $0^{\circ}\mathrm{C}$.

78.With increase in pressure, the speed of sound will: (NUMS MDCAT 2023)

  1. Increase
  2. Decrease
  3. First increase then decrease
  4. Remain the same
Show answer

Correct answer: (d) Remain the same

Raising the pressure raises the density in the same proportion, so the speed is unchanged.

79.If the length of a second's pendulum becomes four times, then its time period will become: (MDCAT 2023)

  1. four times
  2. two times
  3. half
  4. one fourth
Show answer

Correct answer: (b) two times

$T=2\pi\sqrt{l/g}$, so $T$ goes as the square root of the length.

80.When will the oscillations stop in the absence of resistive forces? (UHS MDCAT 2023)

  1. Never
  2. After 10 minutes
  3. In 10 minutes
  4. Immediately
Show answer

Correct answer: (a) Never

With nothing to take energy from it, an oscillator would go on for ever.

81.Reducing mass M of a suspending body to one fourth will change the frequency of oscillation to (UHS MDCAT 2023)

  1. One fourth
  2. Double
  3. Quadrupule
  4. Half
Show answer

Correct answer: (b) Double

The frequency goes as $1/\sqrt{m}$, so a quarter of the mass doubles it.

82.If the length of second pendulum becomes four times, then its time period will become: (UHS MDCAT 2023)

  1. Four times
  2. Two times
  3. Half
  4. One fourth
Show answer

Correct answer: (b) Two times

$T=2\pi\sqrt{l/g}$ goes as the square root of the length, so four times the length doubles the period.

Thermodynamics

83.Thermodynamics is that branch of Physics in which we study (UHS MDCAT 2023)

  1. relations between heat and mechanical energies
  2. relations between heat and ionization energies
  3. relations between chemical and mechanical energies
  4. relations between kinetic and potential energies
Show answer

Correct answer: (a) relations between heat and mechanical energies

Thermodynamics is the study of heat and its relation to mechanical work.

84.When a gas is compressed isothermally, the product of its pressure and volume during the process is: (UHS MDCAT 2023)

  1. not constant
  2. constant
  3. zero
  4. proportional to entropy
Show answer

Correct answer: (b) constant

At constant temperature $PV=nRT$ makes the product constant, which is Boyle’s law.

85.Temperature of given mass of a gas is changed from 150°C to 300°C during an isobaric process, volume of the gas will become: (UHS MDCAT 2023)

  1. Half
  2. Double
  3. Remain same
  4. Less than double
Show answer

Correct answer: (d) Less than double

On the Kelvin scale the temperature rises from $423$ to $573$, a factor of only $1.35$.

86.The thermodynamic process during which volume of the system remains constant is called: (SZABMU MDCAT 2023)

  1. Isothermal
  2. Isobaric
  3. Isochoric
  4. Adiabatic
Show answer

Correct answer: (c) Isochoric

A change at constant volume is isochoric.

87.The conditions for application of Boyle’s law holds good in: (SZABMU MDCAT 2023)

  1. Adiabatic process
  2. Isothermal process
  3. Isobaric process
  4. Isochoric process
Show answer

Correct answer: (b) Isothermal process

Boyle’s law holds at constant temperature, that is in an isothermal change.

88.In isochoric process: (NUMS MDCAT 2023)

  1. Pressure is kept constant
  2. Exchange of heat is zero
  3. Volume is kept constant
  4. Temperature is kept constant
Show answer

Correct answer: (c) Volume is kept constant

Isochoric means at constant volume.

89.The first law of thermodynamics concerns the conservation of: (MDCAT 2023)

  1. heat
  2. work
  3. momentum
  4. energy
Show answer

Correct answer: (d) energy

$\Delta U=Q-W$ is the conservation of energy written for a thermodynamic system.

90.The internal energy of a system during an isothermal process: (SZABMU MDCAT 2023)

  1. Decreases
  2. Increases
  3. Becomes zero
  4. Remains constant
Show answer

Correct answer: (d) Remains constant

Internal energy depends only on temperature, which an isothermal change holds fixed.

91.If 42 J heat is transferred to the system during expansion, what is the change in internal energy when work done is 32 J? (NUMS MDCAT 2023)

  1. 74 J
  2. 10 J
  3. 116 J
  4. 106 J
Show answer

Correct answer: (b) 10 J

$\Delta U=Q-W=42-32$, which is $10\,\mathrm{J}$.

92.The 1st law of thermodynamics is the generalization of the law of conservation of: (NUMS MDCAT 2023)

  1. Mass
  2. Charge
  3. Energy
  4. Momentum
Show answer

Correct answer: (c) Energy

The first law is the conservation of energy applied to heat and work.

93.First law of thermodynamics concerns with the conservation of (UHS MDCAT 2023)

  1. Heat
  2. Work
  3. Momentum
  4. Energy
Show answer

Correct answer: (d) Energy

The first law is the conservation of energy written for heat and work.

94.An ideal gas has molar specific heat $C_p$ at constant pressure. When the temperature of $n$ moles is increased by $\Delta T$, the increase in the internal energy is: (MDCAT 2023)

  1. $nC_p\Delta T$
  2. $n(C_p+R)\Delta T$
  3. $n(C_p-R)\Delta T$
  4. $n(2C_p+R)\Delta T$
Show answer

Correct answer: (c) $n(C_p-R)\Delta T$

$\Delta U=nC_v\Delta T$ and $C_p-C_v=R$, so $C_v=C_p-R$.

Electrostatics

95.As per Coulomb's law, the force of attraction or repulsion between two point charges is directly proportional to the: (MDCAT 2023)

  1. sum of the magnitudes of the charges
  2. product of the magnitudes of the charges
  3. square of the distance between them
  4. distance between them
Show answer

Correct answer: (b) product of the magnitudes of the charges

$F\propto q_1q_2$, and it is inversely proportional to the square of the separation.

96.The Coulomb's constant k depends upon: (UHS MDCAT 2023)

  1. nature of medium
  2. system of units
  3. types of charge
  4. nature of medium and system of units
Show answer

Correct answer: (d) nature of medium and system of units

$k=1/4\pi\varepsilon$ carries the permittivity of the medium, and its number depends on the units used.

97.The electric field intensity inside a charged hollow sphere is: (MDCAT 2023)

  1. maximum
  2. zero
  3. negative
  4. positive
Show answer

Correct answer: (b) zero

The charge resides on the outer surface and its contributions cancel everywhere inside, so the field there is zero.

98.A charged particle moves in a uniform electric field between two oppositely charged parallel metal plates. To calculate the force acting on the particle due to the electric field, which quantity is not required? (UHS MDCAT 2023)

  1. Particle charge
  2. Particle speed
  3. Plate separation
  4. Potential difference between the plates
Show answer

Correct answer: (b) Particle speed

The field is the potential difference over the separation, and the force is $qE$; the speed does not enter.

99.Gauss law cannot be used to find which of the following quantity? (UHS MDCAT 2023)

  1. Electric field intensity
  2. Electric flux density
  3. Charge
  4. Permittivity
Show answer

Correct answer: (d) Permittivity

Permittivity is a property of the medium and must be known before Gauss’s law can be used at all.

100.Electric intensity due to charge distributions are calculated using which following law? (SZABMU MDCAT 2023)

  1. Ohm’s law
  2. Faraday’s law
  3. Gauss’s law
  4. Ampere’s law
Show answer

Correct answer: (c) Gauss’s law

Gauss’s law gives the field of a symmetrical charge distribution from the flux through a closed surface.

101.Electric field intensity inside a hollow charged sphere is: (UHS MDCAT 2023)

  1. Maximum
  2. Zero
  3. Negative
  4. Positive
Show answer

Correct answer: (b) Zero

The charge sits on the surface, so by Gauss’s law the field inside the shell is zero.

102.What is the potential difference between two points in an electric field if it takes 600 J of energy to move a charge of 2 C between these two points? (UHS MDCAT 2023)

  1. 1200 J
  2. 800 J
  3. 300 J
  4. 0 J
Show answer

Correct answer: (c) 300 J

$V=W/q=600/2$, which is $300\,\mathrm{V}$.

103.The SI unit of potential difference is: (SZABMU MDCAT 2023)

  1. Volt
  2. Coulomb
  3. Watt
  4. eV
Show answer

Correct answer: (a) Volt

Potential difference is measured in volts.

104.Electric potential is defined as: (SZABMU MDCAT 2023)

  1. Work per unit charge
  2. Force per unit charge
  3. Power per unit charge
  4. Force
Show answer

Correct answer: (a) Work per unit charge

Potential is the work done per unit charge in bringing it from infinity.

105.1eV is equal to: (SZABMU MDCAT 2023)

  1. 1.602 x 10-19 J
  2. 16.02 x 10-19 J
  3. 1620 J
  4. 162.0 x 10-19 J
Show answer

Correct answer: (a) 1.602 x 10-19 J

An electron volt is $1.602\times10^{-19}\,\mathrm{J}$.

106.A capacitor of capacitance 'C' has a charge 'Q' and stored energy is 'w'. If the charge is increases to '2Q'. The stored energy will be: (UHS MDCAT 2023)

  1. 2W
  2. 4W
  3. W/4
  4. W/2
Show answer

Correct answer: (b) 4W

$U=Q^2/2C$ goes as the square of the charge, so twice the charge stores four times the energy.

107.The capacitance of capacitor does not depend on: (SZABMU MDCAT 2023)

  1. Area of plates
  2. Medium
  3. Distance between plates
  4. Thickness of plates
Show answer

Correct answer: (d) Thickness of plates

$C=\varepsilon A/d$ carries the area, the separation and the medium, but not how thick the plates are.

108.While studying charging and discharging of a capacitor, Rc = Resistance × Capacitance is known as: (NUMS MDCAT 2023)

  1. Electrostatic constant
  2. Time constant
  3. Dielectric constant
  4. Proportionality constant
Show answer

Correct answer: (b) Time constant

$RC$ has the dimension of time and is called the time constant of the circuit.

109.In parallel combination of two capacitors, their equivalent capacitance is equal to: (NUMS MDCAT 2023)

  1. C1 + C2
  2. 1/C1 + 1/C2
  3. C1C2 / C1 + C2
  4. 2C1C2 / C1 + C2
Show answer

Correct answer: (a) C1 + C2

Capacitors in parallel share the same voltage, so their capacitances add.

110.To store the electric charge the ultra-capacitors use _______ effect. (UHS MDCAT 2023)

  1. Single layer
  2. Double layer
  3. Triple layer
  4. Quadruple layer
Show answer

Correct answer: (b) Double layer

An ultracapacitor stores charge in the electrical double layer at the electrode surface.

Current Electricity

111.How much potential drop exist across closed switch? (UHS MDCAT 2023)

  1. 0 V
  2. 1V
  3. 2V
  4. 3V
Show answer

Correct answer: (a) 0 V

A closed switch is a length of conductor with no resistance, so no potential is dropped across it.

112.A 3 V battery is connected in series with ammeter and 2 ohm resistance after short circuiting circuiting. What will be the reading of ammeter? (UHS MDCAT 2023)

  1. 1 A
  2. 1.5 A
  3. 5 A
  4. 6 A
Show answer

Correct answer: (b) 1.5 A

$I=V/R=3/2$, which is $1.5\,\mathrm{A}$.

113.Which of the following statement is NOT CORRECT about Kirchhoff's rule? (UHS MDCAT 2023)

  1. Kirchhoff's current rule based upon the law of conservation of charge
  2. Wheatstone bridge is an application of Kirchhoff's rule
  3. Kirchhoff's rules are more suitable in AC circuits
  4. Kirchhoff's voltage rule based upon the law of conservation of energy
Show answer

Correct answer: (c) Kirchhoff's rules are more suitable in AC circuits

The rules were framed for steady currents; alternating circuits need reactance as well as resistance.

114.Volt × Ampere is the unit of: (NUMS MDCAT 2023)

  1. Current
  2. Volt
  3. Resistance
  4. Power
Show answer

Correct answer: (d) Power

Volts times amperes is watts, the unit of power.

115.The ohmmeter of a portable digital multi meter need: (UHS MDCAT 2023)

  1. Internal battery
  2. Wet cell
  3. Voltmeter
  4. Ammeter
Show answer

Correct answer: (a) Internal battery

An ohmmeter must drive its own current through the resistor, so it carries a battery.

116.A wire of uniform cross-sectional area $A$, length $L$ and resistance $R$ is cut into two equal parts. What will happen to the resistivity of each part? (MDCAT 2023)

  1. it will be doubled
  2. it will be one fourth
  3. it will be halved
  4. it will remain the same
Show answer

Correct answer: (d) it will remain the same

Resistivity depends on the material and its temperature, not on the size of the piece.

117.What do the substances whose resistance decreases with increase in temperature have? (UHS MDCAT 2023)

  1. high temperature coefficient
  2. negative temperature coefficient
  3. positive temperature coefficient
  4. zero temperature coefficient
Show answer

Correct answer: (b) negative temperature coefficient

A substance whose resistance falls as it warms has a negative temperature coefficient.

118.Ohm meter us the unit of: (SZABMU MDCAT 2023)

  1. Resistance
  2. Resistivity
  3. Conductance
  4. conductivity
Show answer

Correct answer: (b) Resistivity

$\rho=RA/L$ has the unit ohm metre.

119.The total resistance of wire isinversely proportional to: (SZABMU MDCAT 2023)

  1. Length
  2. Area
  3. Temperature
  4. Time
Show answer

Correct answer: (b) Area

$R=\rho L/A$, so the thicker the wire the smaller its resistance.

120.If length of the wire becomes two times to its original value and area becomes one half to its original value, then resistance of the wire becomes: (NUMS MDCAT 2023)

  1. Double
  2. Four times
  3. One half
  4. One forth
Show answer

Correct answer: (b) Four times

$R=\rho L/A$ doubles with the length and doubles again as the area is halved.

121.Which of the following the fractional change in resistance per kelvin? (UHS MDCAT 2023)

  1. Conductivity
  2. Resistivity
  3. Temperature coefficient of resistivity
  4. Temperature coefficient of resistance
Show answer

Correct answer: (d) Temperature coefficient of resistance

That fraction is the temperature coefficient of resistance.

122.The following formula can be used to determine the resistance of a length of conductor. R pl/A In the formula, the symbol p stands for the: (UHS MDCAT 2023)

  1. Cross-sectional area of the conductor in m2
  2. Product of the length of the conductor in meters
  3. Resistivity of the material in units of ohm meters
  4. Resistance of the conductor in units of ohms per meter
Show answer

Correct answer: (c) Resistivity of the material in units of ohm meters

In $R=\rho L/A$ the symbol $\rho$ is the resistivity, measured in ohm metres.

123.The resistance of the wire varies inversely as: (UHS MDCAT 2023)

  1. Area of cross section
  2. length
  3. Resistivity
  4. Temperature
Show answer

Correct answer: (a) Area of cross section

$R=\rho L/A$, so the wider the wire the smaller its resistance.

124.A wire of uniform area of cross-section A’, length ‘L’, and resistance R is cut into two equal parts. What will happen to the resistivity of each part? (UHS MDCAT 2023)

  1. It will be doubled
  2. It will be one fourth
  3. It will be halved
  4. It will remain the same
Show answer

Correct answer: (d) It will remain the same

Resistivity is a property of the material, so cutting the wire does not change it.

125.A low voltage supply with an e.m.f. of 20 V and an internal resistance of 1.5 ohms is used to supply power to a heater of resistance 6.5 ohms in a fish tank. What is the power supplied to the water in the fish tank? (UHS MDCAT 2023)

  1. 41 W
  2. 50 W
  3. 53 W
  4. 62 W
Show answer

Correct answer: (a) 41 W

$I=20/8=2.5\,\mathrm{A}$, and $I^2R=6.25\times6.5$ gives about $41\,\mathrm{W}$ in the heater.

Electromagnetism

126.Q.162 The source of magnetic field is: (UHS MDCAT 2023)

  1. An isolated magnetic pole
  2. Static electric charge
  3. Nonmagnetic substance
  4. Current loop
Show answer

Correct answer: (d) Current loop

A magnetic field is made by moving charge, that is by a current.

127.The dimension of magnetic field strength is same as that of: (NUMS MDCAT 2023)

  1. Magnetic flux
  2. Magnetic induction
  3. Work done
  4. Magnetic force
Show answer

Correct answer: (b) Magnetic induction

Magnetic field strength and magnetic induction are the same quantity, measured in tesla.

128.Q.161 Which surface has greater magnetic flux in same magnetic field, each has an area 1 m^2. (UHS MDCAT 2023)

  1. Circular
  2. Rectangular
  3. Square
  4. Flux is independent of shape
Show answer

Correct answer: (d) Flux is independent of shape

Flux is the product of flux density and area, whatever the outline of that area.

129.The weber is unit of measure of: (NUMS MDCAT 2023)

  1. Conductance
  2. Electric current
  3. Magnetic flux
  4. Electric flux
Show answer

Correct answer: (c) Magnetic flux

Magnetic flux is measured in webers.

130.If 0.5 T field is applied over an area of 2-meter square which lies at an angle of 60 degree with the field, then the resulting flux will be: (UHS MDCAT 2023)

  1. 0.5 T
  2. 0.5 Wb
  3. 0.25 Wb
  4. 0.25 T
Show answer

Correct answer: (b) 0.5 Wb

$\Phi=BA\cos\theta=0.5\times2\times\cos60^{\circ}$, which is $0.5\,\mathrm{Wb}$.

131.The magnitude of the magnetic force on a current-carrying conductor in a uniform magnetic field is maximum if the conductor is: (MDCAT 2023)

  1. perpendicular to the magnetic field
  2. parallel to the magnetic field
  3. at $45^\circ$ to the magnetic field
  4. antiparallel to the magnetic field
Show answer

Correct answer: (a) perpendicular to the magnetic field

$F=BIL\sin\theta$ is greatest when $\theta=90^\circ$.

132.Electric forces change the magnitude and direction of velocity while magnetic forces change_____________ of velocity (UHS MDCAT 2023)

  1. Only Magnitude
  2. Only direction
  3. Magnitude and direction
  4. Neither magnitude nor direction
Show answer

Correct answer: (b) Only direction

The magnetic force is always at right angles to the velocity, so it can only turn it.

133.The force exerted on charged particle will be maximum when it enters the magnetic field at: (SZABMU MDCAT 2023)

  1. 60O
  2. 90O
  3. 0O
  4. 45O
Show answer

Correct answer: (b) 90O

$F=qvB\sin\theta$ is greatest when the particle crosses the field at a right angle.

134.The magnitude of magnetic force will be maximum on current carrying conductor in uniforrn magnetic field if conductor is placed? (UHS MDCAT 2023)

  1. Parallel to magnetic field
  2. At 45 degree in magnetic field
  3. Perpendicular to magnetic field
  4. Antiparallel in magnetic field
Show answer

Correct answer: (c) Perpendicular to magnetic field

$F=BIL\sin\theta$ is greatest when the conductor lies across the field.

135.When a charged particle enters the magnetic field parallel then it will: (SZABMU MDCAT 2023)

  1. Deflect toward north
  2. Deflect toward south
  3. Move straight
  4. Move in circular path
Show answer

Correct answer: (c) Move straight

With the velocity along the field the sine is zero, so there is no force and the path stays straight.

136.When a charged particle enters the magnetic field parallel, it will: (NUMS MDCAT 2023)

  1. Deflect toward north
  2. Deflect toward south
  3. Move straight
  4. Move in circular path
Show answer

Correct answer: (c) Move straight

With the velocity along the field there is no force, so the path is a straight line.

Electromagnetic Induction

137.Q.163 One meter long copper rod is moving with speed 20 m/sec in the magnetic field of strength 0.6 tesla. What is the value of induced emf ? (UHS MDCAT 2023)

  1. 10 v
  2. 12 v
  3. 14 v
  4. 16 v
Show answer

Correct answer: (b) 12 v

$\varepsilon=BLv=0.6\times1\times20$, which is $12\,\mathrm{V}$.

138.Q.164 The unit of Δφ/Δt can be written as ? (UHS MDCAT 2023)

  1. NmA^-2s^-1
  2. NmAs^-1
  3. NmA^-1s^-1
  4. NmA^-2s1
Show answer

Correct answer: (c) NmA^-1s^-1

The rate of change of flux is an emf, that is a volt, and a volt is $\mathrm{N\,m\,A^{-1}\,s^{-1}}$.

139.Q.166 A copper hoop is held in a vertical east-west plane in a uniform magnetic field whose field lines run along the north-south direction. The largest induced emf is produced when the hoop is ? (UHS MDCAT 2023)

  1. Rotated about a north-south axis
  2. Rotated about an east-west axis
  3. Moved rapidly, without rotation, toward the east
  4. Moved rapidly, without rotation, toward the south
Show answer

Correct answer: (b) Rotated about an east-west axis

Turning about the east-west axis sweeps the plane of the hoop right through the north-south field lines.

140.In Fleming’s right hand rule the middle finger indicates: (SZABMU MDCAT 2023)

  1. Force
  2. Magnetic field
  3. Induced current
  4. Volt
Show answer

Correct answer: (c) Induced current

Thumb for motion, first finger for field, second finger for the induced current.

141.In Fleming's right hand rule, the second finger indicates: (NUMS MDCAT 2023)

  1. Force
  2. Magnetic field
  3. Induced current
  4. Motion
Show answer

Correct answer: (c) Induced current

Thumb for motion, first finger for field, second finger for the induced current.

142.A current generator is a device that converts: (NUMS MDCAT 2023)

  1. Mechanical energy into electrical energy
  2. Chemical energy into mechanical energy
  3. Sound energy into mechanical energy
  4. Electrical energy into mechanical energy
Show answer

Correct answer: (a) Mechanical energy into electrical energy

A generator turns the work done in rotating the coil into electrical energy.

143.The expression for the emf produced by A. C. generator is? (UHS MDCAT 2023)

  1. NωAB Sinθ
  2. NωAB Cosθ
  3. NωAB
  4. ILB Cosθ
Show answer

Correct answer: (a) NωAB Sinθ

The emf of a rotating coil is $NAB\omega\sin\theta$.

144.The induced emf produced in the coil is sometimes called as? (UHS MDCAT 2023)

  1. Self-inductance
  2. Back emf
  3. Motional emf
  4. Mutual inductance
Show answer

Correct answer: (b) Back emf

The emf induced in a coil by its own changing current opposes that current, so it is called the back emf.

145.Q.165 Working principal of magnetic levitation train is according to ? (UHS MDCAT 2023)

  1. Faraday law
  2. Max planks law
  3. Ohm law
  4. Lenz law
Show answer

Correct answer: (d) Lenz law

The induced currents oppose the approaching magnet, and the repulsion is what lifts the train.

146.Lenz’s law is also a statement of law of conservation of: (SZABMU MDCAT 2023)

  1. Charge
  2. Energy
  3. Momentum
  4. Mass
Show answer

Correct answer: (b) Energy

If the induced current helped the change, energy would be created out of nothing.

147.The Lenz's law is also statement of law of conservation of: (NUMS MDCAT 2023)

  1. Charge
  2. Mass
  3. Energy
  4. Pressure
Show answer

Correct answer: (c) Energy

If the induced current helped the change, energy would be made from nothing.

148.In principle, a transformer consists of two coils of copper, electrically insulated from each other, wound on the same: (MDCAT 2023)

  1. iron core
  2. copper core
  3. gold core
  4. steel core
Show answer

Correct answer: (a) iron core

A soft iron core carries almost all the flux of the primary through the secondary.

149.Q.167 In transformer, there is no ______ connection between the two coils but they are ______ linked ? (UHS MDCAT 2023)

  1. Magnetic, electrically
  2. Electrical, magnetically
  3. Magnetic, magnetically
  4. Electrical, optically
Show answer

Correct answer: (b) Electrical, magnetically

The coils share no wire; they are coupled only by the flux in the common core.

150.Transformer works on the principle of: (SZABMU MDCAT 2023)

  1. Lenz’s Law
  2. Faraday’s Law
  3. Mutual Induction
  4. Ampere’s Law
Show answer

Correct answer: (c) Mutual Induction

The changing flux of the primary induces an emf in the secondary, which is mutual induction.

151.The efficiency of transformer is: (SZABMU MDCAT 2023)

  1. 60 %
  2. 70 %
  3. 80 %
  4. 90 %
Show answer

Correct answer: (d) 90 %

A well made transformer wastes little, so its efficiency is around ninety per cent or better.

152.In principle, the transformer consists of two coils of copper, electrically insulated from each other, wound on the same? (UHS MDCAT 2023)

  1. Iron core
  2. Copper core
  3. Gold core
  4. Steel core
Show answer

Correct answer: (a) Iron core

A soft iron core carries the flux from one winding to the other with little loss.

Alternating Current

153.Red light is used in photographic dark room because of: (SZABMU MDCAT 2023)

  1. More frequency, less wavelength
  2. Less frequency, less wavelength
  3. Less frequency, more wavelength
  4. More frequency, more wavelength
Show answer

Correct answer: (c) Less frequency, more wavelength

Red is at the low frequency, long wavelength end, so its photons carry too little energy to expose the film.

Electronics

154.Q.168 When the temperature of semiconductor suddenly drops to zero kelvin, then a semiconductor acts as: (UHS MDCAT 2023)

  1. Conductor
  2. Semi-conductor
  3. Super conductor
  4. Insulator
Show answer

Correct answer: (d) Insulator

At absolute zero no electron has the energy to cross the gap, so no charge can move.

155.A process in which only one half of alternating current is converted into direct current is called: (SZABMU MDCAT 2023)

  1. Full wave rectification
  2. Amplification
  3. Half wave rectification
  4. Magnification
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Correct answer: (c) Half wave rectification

A single diode passes only the half cycles of one sign, which is half wave rectification.

156.Efficiency of full wave rectifier circuit is almost________than half wave rectifier circuit: (SZABMU MDCAT 2023)

  1. Four times
  2. Same as
  3. Sixteen times
  4. Double
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Correct answer: (d) Double

Both half cycles are used instead of one, so the output is about twice as effective.

157.The conversion of alternating current into direct current is called rectification and circuit is called rectifier. Which component of electronics acts as a rectifier? (SZABMU MDCAT 2023)

  1. Diode
  2. Transistor
  3. Transformer
  4. Inductor
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Correct answer: (a) Diode

A diode passes current one way only, which is what rectification needs.

158.A device that converts AC into DC is called: (NUMS MDCAT 2023)

  1. Diode
  2. Transistor
  3. Capacitor
  4. Inductor
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Correct answer: (a) Diode

A diode passes current one way only, so it turns alternating into direct current.

159.The conversion of alternating current into direct current is called: (NUMS MDCAT 2023)

  1. Amplification
  2. Rectification
  3. Magnification
  4. Resolution
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Correct answer: (b) Rectification

That process is rectification.

160.In full wave rectification, ________ diodes are used. (NUMS MDCAT 2023)

  1. 1
  2. 2
  3. 3
  4. 4
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Correct answer: (d) 4

A bridge rectifier uses four diodes, two conducting on each half cycle.

Dawn of Modern Physics

161.Q.169 If electron, proton, neutron, and alpha particle have same velocity, which of them has the shortest wavelength? (UHS MDCAT 2023)

  1. Electron
  2. Proton
  3. Neutron
  4. Alpha particle
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Correct answer: (d) Alpha particle

At the same speed the alpha particle has much the largest momentum, and $\lambda=h/mv$ is smallest for it.

162.Q.170 The process of ejection of loosely bound electrons from a certain photo sensitive surface by absorption of photon is called: (UHS MDCAT 2023)

  1. Compton effect
  2. Photoelectric effect
  3. Pair production
  4. Black body radiation
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Correct answer: (b) Photoelectric effect

That is the photoelectric effect.

163.Q.171 In a photoelectric effect experiment, the stopping potential is: (UHS MDCAT 2023)

  1. The kinetic energy of the most energetic electron ejected
  2. The potential energy of the most energetic electron ejected
  3. The photon energy
  4. The electric potential that causes the electron current to vanish
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Correct answer: (d) The electric potential that causes the electron current to vanish

The stopping potential is the reverse voltage at which even the fastest electron fails to reach the anode.

164.Which photons carries the most energy? (SZABMU MDCAT 2023)

  1. Blue
  2. Violet
  3. Red
  4. Green
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Correct answer: (b) Violet

Energy is $hf$, and violet has the highest frequency of the four.

Atomic Spectra

165.Which of the following is the longest wavelength available for the Paschen series? (MDCAT 2023)

  1. $1.87\times10^{8}\ \mathrm{m}$
  2. $1.87\times10^{8}\ \mathrm{m^{-1}}$
  3. $1.87\times10^{-6}\ \mathrm{m}$
  4. $1.87\times10^{-6}\ \mathrm{m^{-1}}$
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Correct answer: (c) $1.87\times10^{-6}\ \mathrm{m}$

The longest wavelength of a series comes from its smallest energy step, $n=4\to3$, and is about $1.87\times10^{-6}$ m, in the infrared.

166.Q.172 The line spectrum of hydrogen atom contains the spectral lines in the region of: (UHS MDCAT 2023)

  1. ultraviolet
  2. infrared
  3. visible
  4. all of these
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Correct answer: (d) all of these

The Lyman lines are ultraviolet, the Balmer visible, and the rest infrared.

167.Q.173 The speed of electron in the first Bohr orbit is: (UHS MDCAT 2023)

  1. 2.19 x 10^6 ms^-1
  2. 2.19 x 10^-6 ms^-1
  3. 2.19x 10^4 ms^-1
  4. 2.19 x 10^-4 ms^-1
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Correct answer: (a) 2.19 x 10^6 ms^-1

In the first Bohr orbit the electron moves at about $2.19\times10^6\,\mathrm{m\,s^{-1}}$.

168.Which one of the following series lies in the ultraviolet region? (SZABMU MDCAT 2023)

  1. Balmer series
  2. Paschen series
  3. Lyman series
  4. Bracket series
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Correct answer: (c) Lyman series

The Lyman lines end on the ground level and lie in the ultraviolet.

169.Which x-ray photon will have longest wavelength? (SZABMU MDCAT 2023)

  1. Kα
  2. Kβ
  3. Kγ
  4. Mα
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Correct answer: (a) Kα

The K alpha line comes from the smallest energy drop of the K series, so its wavelength is the longest.

170.The Balmer series of hydrogen is important because it: (UHS MDCAT 2023)

  1. Is the only one for which the quantum theory can be used
  2. Is the only series that occurs for hydrogen
  3. Is in the visible region
  4. Involves the lowest possible quantum number n
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Correct answer: (c) Is in the visible region

The Balmer lines end on the second level, and they are the ones the eye can see.

Nuclear Physics

171.Q.175 It has been observed that Thorium (_90^234)Th is transformed into Protactinium (_91^234)Pa after the emission of ______________ particle: (UHS MDCAT 2023)

  1. Alpha
  2. Beta
  3. Gamma
  4. Alpha, Beta, Gamma
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Correct answer: (b) Beta

The mass number is unchanged and the atomic number rises by one, which is beta emission.

172.Q.176 The half-life of Strontium (Sr) is 8.70 hours. Its decay constant is: (UHS MDCAT 2023)

  1. 0.000022 s
  2. 45000 /s
  3. 0.000022 / s
  4. 0.000032 / s
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Correct answer: (c) 0.000022 / s

$\lambda=0.693/t_{1/2}=0.693/(8.70\times3600)$, about $2.2\times10^{-5}\,\mathrm{s^{-1}}$.

173.The decay rate of radioactive substance is: (UHS MDCAT 2023)

  1. Constant with time
  2. Varies inversely with time
  3. Decreases exponentially with time
  4. Decreases linearly with time
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Correct answer: (c) Decreases exponentially with time

The activity is proportional to the number left, and that falls exponentially.

174.The half-life of Iodine – 31 is: (SZABMU MDCAT 2023)

  1. 10 days
  2. 8 days
  3. 45 days
  4. 60 days
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Correct answer: (b) 8 days

Iodine-131 has a half life of about eight days.

175.The half-life of carbon is 5730 years. How much carbon will left after 22920 years? (SZABMU MDCAT 2023)

  1. 1/32nd
  2. 1/16th
  3. 1/64th
  4. 1/4th
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Correct answer: (b) 1/16th

$22920/5730$ is four half lives, and each halves what is left, leaving a sixteenth.

176.The time taken for half the number of atoms of radioactive isotopes to disintegrate is called: (NUMS MDCAT 2023)

  1. Average life
  2. Mean life
  3. Total life
  4. Half life
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Correct answer: (d) Half life

That time is the half life.

177.A 32g radioactive element decays and remains 2g after 60 days. What is half-life of this radioactive element? (NUMS MDCAT 2023)

  1. 2 days
  2. 6 days
  3. 10 days
  4. 15 days
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Correct answer: (d) 15 days

Going from $32$ to $2\,\mathrm{g}$ is four half lives, and $60/4$ is $15$ days.

178.Q.174 A low energy neutron has RBE factor of 10. How much energy is absorbed by a man of mass 80 Kg if the value of equivalent dose is 400 rem? (UHS MDCAT 2023)

  1. 16 J
  2. 32 J
  3. 48 J
  4. 64 J
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Correct answer: (b) 32 J

$400\,\mathrm{rem}$ with an RBE of ten is $40\,\mathrm{rad}$, that is $0.4\,\mathrm{J\,kg^{-1}}$, and $0.4\times80$ is $32\,\mathrm{J}$.

179.Skin burns, loss of hair, drop in the white blood cells etc. are examples of: (SZABMU MDCAT 2023)

  1. Somatic effect
  2. Genetic effect
  3. Metabolism effect
  4. Mutation effect
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Correct answer: (a) Somatic effect

These appear in the person irradiated, so they are somatic effects.

180.The SI unit of equivalent dose is: (UHS MDCAT 2023)

  1. Gray
  2. Mass
  3. Rad
  4. Sievert
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Correct answer: (d) Sievert

Equivalent dose is measured in sieverts.

Other MDCAT past papers