MDCAT 2025 Physics

MDCAT 2025 Physics Past Paper MCQs with Answers

161 Physics MCQs that appeared in MDCAT 2025, arranged unit by unit in syllabus order. Tap “Show answer” under any question for the correct option and a short solution.

Vectors and Equilibrium

1.Consider these two vectors A = 2i + 3j and B = -6i + 4j. The angle between these two vectors is: (SIBA MDCAT 2025)

  1. 60°
  2. 90°
  3. 120°
  4. 180°
Show answer

Correct answer: (b) 90°

The scalar product is $-12+12=0$, so the vectors are at right angles.

Force and Motion

2.A body moves along a semicircular path of radius 10 m from one end of the diameter to the other. The ratio of distance to displacement is: (SIBA MDCAT 2025)

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

Correct answer: (c) π : 2

The path is $\pi r$ and the displacement is the diameter $2r$, so the ratio is $\pi:2$.

3.A person moves 600 m towards north then 300 m towards south. Its displacement to distance ratio is: (SZABMU MDCAT 2025)

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

The displacement is $300\,\mathrm{m}$ and the distance walked is $900\,\mathrm{m}$, a ratio of $1:3$.

4.A displacement time graph is a straight line inclined up at angle of 45° with X-axis, velocity of body according to this graph is: (SIBA MDCAT 2025)

  1. Increasing
  2. Decreasing
  3. Constant
  4. Decreasing at start and then may decrease
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Correct answer: (c) Constant

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

5.A car starts from rest and moves with a uniform acceleration of 3m/s^2. What will be its velocity after 5 seconds? (KMU MDCAT 2025)

  1. 8m/s
  2. 12m/s
  3. 15m/s
  4. 18m/s
Show answer

Correct answer: (c) 15m/s

$v=at=3\times5$, which is $15\,\mathrm{m\,s^{-1}}$.

6.Unequal changes occurring in velocity of a body is called (SZABMU MDCAT 2025)

  1. Uniform acceleration
  2. Instantaneous acceleration
  3. variable acceleration
  4. Uniform velocity
Show answer

Correct answer: (c) variable acceleration

Unequal changes of velocity in equal times are a variable acceleration.

7.A ball is thrown into the air with certain velocity v making an angle θ with horizontal. If air resistance is neglected, then at maximum height its velocity is: (UHS MDCAT 2025)

  1. Equal to initial velocity
  2. Half of initial velocity
  3. Equal to zero
  4. Minimum but not zero
Show answer

Correct answer: (d) Minimum but not zero

The vertical component is spent at the top, but the horizontal component is carried right through.

8.A projectile is launched in air with certain angle; its velocity is maximum at: (UHS MDCAT 2025)

  1. Point of projection
  2. Highest point
  3. Between launching and highest point
  4. At all points
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Correct answer: (a) Point of projection

The projectile is slowest at the top and fastest where it started, before gravity has taken any of the vertical component.

9.Which of the following statement about projectile motion is CORRECT? (KMU MDCAT 2025)

  1. The horizontal velocity of a projectile changes constantly due to gravity
  2. The vertical velocity of a projectile remains constant throughout the flight
  3. At the highest point, the vertical velocity of the projectile is zero, but the horizontal velocity remains unchanged
  4. The acceleration of the projectile is zero at the peak of its trajectory
Show answer

Correct answer: (c) At the highest point, the vertical velocity of the projectile is zero, but the horizontal velocity remains unchanged

Gravity acts only downwards, so it empties the vertical component at the top and leaves the horizontal one alone.

10.If the horizontal range of a projectile becomes half of its maximum possible horizontal range, the probable angle of projection is; (UHS MDCAT 2025)

  1. 15º
  2. 30º
  3. 45º
  4. 60º
Show answer

Correct answer: (a) 15º

The range is largest at $45^{\circ}$, and half of it needs $\sin2\theta=0.5$, so $\theta$ is $15^{\circ}$.

11.Angle at which maximum range of projectile is achieved? (NUMS MDCAT 2025)

  1. 0°
  2. 45°
  3. 90°
  4. 76°
Show answer

Correct answer: (b) 45°

The range goes as $\sin2\theta$, which is largest at $\theta=45^{\circ}$.

12.A body is projected with speed v making an angle θ with the horizontal and covers horizontal range R. If its speed is doubled, the new range will be: (SIBA MDCAT 2025)

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

The range goes as the square of the speed, so doubling the speed gives four times the range.

13.Two balls thrown with equal speeds but at different angles cover equal horizontal distance. If one is thrown at an angle of 40°, then the angle of projection of the other is: (SZABMU MDCAT 2025)

  1. 20°
  2. 30°
  3. 45°
  4. 50°
Show answer

Correct answer: (d) 50°

Two angles adding to $90^{\circ}$ give the same range, so the other is $50^{\circ}$.

14.A passenger standing in a stationary bus. When the bus suddenly starts moving forward, the passenger falls backward. Which phenomenon best explains this observation? (KMU MDCAT 2025)

  1. Friction
  2. Gravity
  3. Inertia
  4. Deceleration
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Correct answer: (c) Inertia

The passenger keeps the state of rest while the floor moves forward under them.

15.Product of force and time is equal to: (NUMS MDCAT 2025)

  1. Change in displacement
  2. Change in momentum
  3. Change in velocity
  4. Change in acceleration
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Correct answer: (b) Change in momentum

Force times time is impulse, and impulse equals the change in momentum.

16.A 150 kg car has its velocity reduced from 20 m/s to 10 m/s in 3.0 sec. How large was the average retarding force? (SIBA MDCAT 2025)

  1. 500 N
  2. 2500 N
  3. 1500 N
  4. 1000 N
Show answer

Correct answer: (a) 500 N

$F=m\Delta v/\Delta t=150\times10/3$, which is $500\,\mathrm{N}$.

17.A ball of mass m strikes a wall and rebounds with the same speed in the opposite direction, taking the initial direction as positive, the change in the momentum of the ball is: (SIBA MDCAT 2025)

  1. 0
  2. mv
  3. -2mv
  4. -mv
Show answer

Correct answer: (c) -2mv

The momentum goes from $mv$ to $-mv$, a change of $-2mv$.

18.A canon is placed on a smooth surface. When it fires a shell, the canon moves backward, this recoil occurs due to: (UHS MDCAT 2025)

  1. law of conservation of energy
  2. Backward thrust of the gases
  3. Newton's third law of motion
  4. Newton's first law of motion
Show answer

Correct answer: (c) Newton's third law of motion

The shell is pushed forward and the cannon takes an equal and opposite push backwards.

19.A 0.02kg bullet moving at 300m/s embeds itself in a 2 kg block at rest on a smooth surface. What is the velocity of the block-bullet system just after impact? (KMU MDCAT 2025)

  1. 2m/s
  2. 3m/s
  3. 4m/s
  4. 5m/s
Show answer

Correct answer: (b) 3m/s

Momentum is conserved, so $0.02\times300$ is shared by $2.02\,\mathrm{kg}$, giving about $3\,\mathrm{m\,s^{-1}}$.

20.If a body having mass m1 (2 kg), moving with 5 m/s approaches another mass, m2 (3 kg) with speed of 1 m/s in same direction, relative speed of approach is 4 m/s. Relative speed of separation after collision will be: (UHS MDCAT 2025)

  1. 4 m/s
  2. 2 m/s
  3. 6 m/s
  4. depends on masses
Show answer

Correct answer: (a) 4 m/s

In a perfectly elastic collision the relative speed of separation equals the relative speed of approach.

21.A body of mass 2 kg moving with velocity 3 m/s collides with a body of mass 1 kg at rest. If they stick together, their common velocity after collision is: (SZABMU MDCAT 2025)

  1. 1 m/s
  2. 2 m/s
  3. 3 m/s
  4. 4 m/s
Show answer

Correct answer: (b) 2 m/s

Momentum is conserved, so $2\times3$ is shared by $3\,\mathrm{kg}$, giving $2\,\mathrm{m\,s^{-1}}$.

Work and Energy

22.Work done is positive if angle is: (NUMS MDCAT 2025)

  1. 0° < θ < 90°
  2. 0° < θ < 180°
  3. 90° < θ < 270°
  4. None of these
Show answer

Correct answer: (a) 0° < θ < 90°

$W=Fd\cos\theta$ is positive while the cosine is positive, that is for angles under $90^{\circ}$.

23.The work done by centripetal force is: (NUMS MDCAT 2025)

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

Correct answer: (c) Zero

The centripetal force is always at right angles to the motion, so it does no work.

24.When force and displacement are in opposite direction then the work done is said to be: (SIBA MDCAT 2025)

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

Correct answer: (b) Negative

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

25.If P is the momentum of an object and m is its mass, then its kinetic energy is: (UHS MDCAT 2025)

  1. P/2m
  2. P^2/2m
  3. 1/2 Pm^2
  4. 1/2 P^2/m^2
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Correct answer: (b) P^2/2m

From $p=mv$, $v=p/m$, so $K=\tfrac12 mv^2$ becomes $p^2/2m$.

26.Earth receives large amount of energy directly from: (UHS MDCAT 2025)

  1. Wind
  2. Water
  3. Sun
  4. Moon
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Correct answer: (c) Sun

Sunlight is the energy the Earth receives directly; wind and water carry it only after it has arrived.

27.A 0.5 kg ball moving at 6 m/s has kinetic energy (UHS MDCAT 2025)

  1. 9 J
  2. 18 J
  3. 6 J
  4. 3 J
Show answer

Correct answer: (a) 9 J

$K=\tfrac12\times0.5\times6^2$, which is $9\,\mathrm{J}$.

28.If velocity is doubled, what happens to kinetic energy: (NUMS MDCAT 2025)

  1. Remains same
  2. Doubles
  3. Quadruples
  4. Halves
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Correct answer: (c) Quadruples

$K=\tfrac12mv^2$ goes as the square of the speed, so twice the speed is four times the energy.

29.The work done on a body is stored in it in the form of: (SZABMU MDCAT 2025)

  1. Power
  2. Energy
  3. Momentum
  4. Impulse
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Correct answer: (b) Energy

The work done on a body appears as its energy.

30.The work done by the gravitational force on an object as it moves from a reference level to a higher point is (UHS MDCAT 2025)

  1. Always positive
  2. Always negative
  3. Zero
  4. Depends on the path taken
Show answer

Correct answer: (b) Always negative

Gravity acts downwards while the body rises, so the force and the displacement are opposed and the work is negative.

31.A 5kg body falls from the height of 30m towards the ground. All its potential energy is converted into heat on impact. What is the heat energy produced? (KMU MDCAT 2025)

  1. 1270J
  2. 1370J
  3. 1470J
  4. 1570J
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Correct answer: (c) 1470J

$mgh=5\times9.8\times30$, which is $1470\,\mathrm{J}$.

32.Potential energy decreases in the process of: (SIBA MDCAT 2025)

  1. Compressing a spring
  2. Stretching a spring
  3. Releasing a stretched spring
  4. Holding the spring at maximum extension
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Correct answer: (c) Releasing a stretched spring

A stretched spring gives up its stored energy as it returns to its natural length.

33.A diver of mass m is swimming at a depth h below the sea level. If the reference level is taken at sea level, the gravitational potential energy of the diver is: (SIBA MDCAT 2025)

  1. 0
  2. mgh
  3. -mgh
  4. 2mgh
Show answer

Correct answer: (c) -mgh

The diver is below the reference level, so the potential energy is negative.

34.The rate of doing work at any instant of time is called: (KMU MDCAT 2025)

  1. Work done
  2. Instantaneous power
  3. Average power
  4. Mechanical energy
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Correct answer: (b) Instantaneous power

Instantaneous power is the rate of doing work at a given moment.

35.Two students, A and B, each carry a 20kg load to the top of a long staircase. Student A takes 10sec, while student B takes 20sec. Which statement is CORRECT? (KMU MDCAT 2025)

  1. Student A does more work than student B
  2. Student B uses more power than student A
  3. Both students do the same amount of work, but student A uses more power
  4. Student A and B use the same power since they lifted the same weight
Show answer

Correct answer: (c) Both students do the same amount of work, but student A uses more power

The same load raised the same height is the same work, and the one who takes half the time delivers twice the power.

36.1 kWh is equal to: (NUMS MDCAT 2025)

  1. 3.6 MW
  2. 3.6 MJ
  3. 3.6 kJ
  4. 3.6 GJ
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Correct answer: (b) 3.6 MJ

A kilowatt for an hour is $1000\times3600$ joules, that is $3.6\,\mathrm{MJ}$.

37.A constant force F acts on a body and displaces it by distance Δd in a time Δt. The rate at which force is doing work is: (SIBA MDCAT 2025)

  1. F x Δd
  2. F x Δt
  3. F x Δd/Δt
  4. F x Δt/Δd
Show answer

Correct answer: (c) F x Δd/Δt

Power is work over time, that is $F\Delta d/\Delta t$.

Rotational and Circular Motion

38.An angular displacement of 90° is equal to: (UHS MDCAT 2025)

  1. One-fourth revolution
  2. One- third revolution
  3. One half revolution
  4. One complete revolution
Show answer

Correct answer: (a) One-fourth revolution

One revolution is $360^{\circ}$, so $90^{\circ}$ is a quarter of it.

39.The angle formed at the center of a circle as a body moves from one position to another is: (SIBA MDCAT 2025)

  1. Angular displacement
  2. Angular velocity
  3. Angular acceleration
  4. Angular momentum
Show answer

Correct answer: (a) Angular displacement

The angle swept at the centre is the angular displacement.

40.A body moving in a circle, half revolution in terms of radians is equivalent to: (SIBA MDCAT 2025)

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

Correct answer: (a) π

A whole revolution is $2\pi$ radians, so half of one is $\pi$.

41.The true statement about angular displacement is: (SZABMU MDCAT 2025)

  1. It always increases with time
  2. It is treated as vector for small rotations
  3. It is always a scalar quantity
  4. It is measured in meters
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Correct answer: (b) It is treated as vector for small rotations

Only for small rotations does angular displacement obey the commutative law of vector addition.

42.π radians are equivalent to (SZABMU MDCAT 2025)

  1. 30°
  2. 270°
  3. 90°
  4. 180°
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Correct answer: (d) 180°

A half revolution is $\pi$ radians, that is $180^{\circ}$.

43.If an object is moving anticlockwise along a circular path, in a horizontal plane on a page then the direction of its angular velocity is: (KMU MDCAT 2025)

  1. Tangential to any point on the circle
  2. Towards centre of the circle
  3. Perpendicular to the plane and pointing out of the page
  4. Perpendicular to the plane and pointing into the page
Show answer

Correct answer: (c) Perpendicular to the plane and pointing out of the page

By the right hand rule an anticlockwise rotation gives an angular velocity out of the page.

44.Direction of angular velocity can be found by: (NUMS MDCAT 2025)

  1. Right-hand rule
  2. Fleming's left-hand rule
  3. Lenz's law
  4. Faraday's law
Show answer

Correct answer: (a) Right-hand rule

Curl the fingers along the rotation and the thumb gives the direction of the angular velocity.

45.If a particle moves along a circular path of radius r with angular displacement θ (in radians), then the arc length s is given by: (KMU MDCAT 2025)

  1. rθ
  2. r/θ
  3. θ/r
  4. 2πrθ
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Correct answer: (a) rθ

With the angle in radians the arc is $s=r\theta$.

46.In circular motion, if angular displacement is kept constant, decreasing the radius will: (SIBA MDCAT 2025)

  1. Increase linear displacement
  2. Increase linear velocity
  3. Decrease linear displacement
  4. Not affect linear displacement
Show answer

Correct answer: (c) Decrease linear displacement

With $s=r\theta$ and the angle fixed, a smaller radius gives a shorter arc.

Fluid Dynamics

47.A ball of weight Fg is falling vertically downward through air. If the drag force acting on it at some instant is Fd, what is the Fnet (net force) on the ball? (KMU MDCAT 2025)

  1. Fg + Fd
  2. Fg - Fd
  3. Fd - Fg
  4. Fd/Fg
Show answer

Correct answer: (b) Fg - Fd

Drag acts upwards against the fall, so the net downward force is the weight less the drag.

48.A body of mass 10 kg is falling through a viscous medium and reached terminal velocity. The net force on the body will be: (SIBA MDCAT 2025)

  1. 0 N
  2. 9.8 N
  3. 98 N
  4. 980 N
Show answer

Correct answer: (a) 0 N

At terminal velocity the drag and upthrust balance the weight, so there is no net force.

49.When a droplet reaches terminal velocity, its acceleration is: (SIBA MDCAT 2025)

  1. Zero
  2. Variable
  3. Not changed
  4. Negative
Show answer

Correct answer: (a) Zero

Terminal velocity is a steady velocity, so the acceleration has fallen to zero.

50.A fluid is flowing through a tube, to undergo transition from laminar to turbulent flow it's velocity must be: (UHS MDCAT 2025)

  1. Slightly less than critical velocity
  2. equal to critical velocity
  3. greater than critical velocity
  4. increasing gradually but less than critical velocity
Show answer

Correct answer: (c) greater than critical velocity

Flow stays laminar up to the critical velocity and turns turbulent once that value is passed.

51.Most kinds of fluid flow are turbulent rather than laminar because of: (KMU MDCAT 2025)

  1. Zero viscosity
  2. Very low velocities
  3. High velocities
  4. No resistance
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Correct answer: (c) High velocities

Beyond the critical speed the layers break up, and most real flows are above it.

52.In laminar flow of fluid, its adjacent layers: (SIBA MDCAT 2025)

  1. Resist each other
  2. Mix with each other
  3. Slide smoothly pass each other
  4. Produce turbulence
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Correct answer: (c) Slide smoothly pass each other

In laminar flow the layers glide over one another without mixing.

53.An incompressible fluid flows through a pipe that becomes narrower in one section. The fluid speed in that region increases in that region to maintain: (UHS MDCAT 2025)

  1. Constant pressure
  2. constant energy
  3. constant mass flow rate
  4. constant volume
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Correct answer: (c) constant mass flow rate

What enters the pipe each second must leave it, so a narrower section is passed at a greater speed.

54.According to law of continuity, when the cross-sectional area of a pipe decreases, the fluid velocity: (KMU MDCAT 2025)

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

Correct answer: (a) Increases

The product of area and speed is constant, so a narrower pipe is passed faster.

55.Water flows through a pipe of 0.02 m^2 with a speed of 3 m/s. The pipe narrows to 0.01 m^2. The speed in narrow section is: (SZABMU MDCAT 2025)

  1. 1.5 m/s
  2. 3 m/s
  3. 6 m/s
  4. 9 m/s
Show answer

Correct answer: (c) 6 m/s

$A_1v_1=A_2v_2$, so $0.02\times3=0.01\times v_2$ and $v_2$ is $6\,\mathrm{m\,s^{-1}}$.

56.In a pipe of varying cross-section as fluid enters the narrower region, it exhibits: (UHS MDCAT 2025)

  1. high velocity, high pressure
  2. high velocity, low pressure
  3. low velocity, high pressure
  4. low velocity, low pressure
Show answer

Correct answer: (b) high velocity, low pressure

Bernoulli’s equation trades pressure for speed, so the fast narrow section is the low pressure one.

57.Water flows steadily through a pipe that gradually narrows. At the wider end, the velocity of water is 1m/s, at the narrower end, the velocity is 3m/s. Which statement is CORRECT about the pressure in the narrower end compared to the wider end? (KMU MDCAT 2025)

  1. Pressure is lower at the narrow end because velocity is higher
  2. Pressure is higher at the narrow end because velocity is higher
  3. Pressure is the same at both ends since flow is continuous
  4. Pressure is independent of velocity of water
Show answer

Correct answer: (a) Pressure is lower at the narrow end because velocity is higher

Bernoulli’s equation trades pressure for speed, so the faster narrow end is at the lower pressure.

58.The increase in kinetic energy associated with decreased pressure of a fluid in a horizontal pipe is a consequence of the: (SIBA MDCAT 2025)

  1. Bernoulli's Principle
  2. Equation of continuity
  3. Pascal's principle
  4. Torricelli's theorem
Show answer

Correct answer: (a) Bernoulli's Principle

Bernoulli’s principle is the statement that pressure falls where the speed of a fluid rises.

59.The curved shape of an airplane wing causes air to move faster over the top surface. This leads to: (UHS MDCAT 2025)

  1. greater pressure on the top
  2. lower pressure on the top
  3. equal pressure on both sides
  4. zero pressure above the wing
Show answer

Correct answer: (b) lower pressure on the top

Faster air over the curved upper surface leaves a lower pressure there, and the difference is the lift.

60.In the human circulatory system, turbulent blood flow is most likely to occur when the: (SZABMU MDCAT 2025)

  1. Vessel diameter is very small
  2. Velocity of blood is very low
  3. Blood flows through a clogged vessel
  4. Blood viscosity increases
Show answer

Correct answer: (c) Blood flows through a clogged vessel

A deposit narrows the vessel and roughens it, so the speed rises past the critical value and the flow breaks up.

Waves

61.Mechanical waves cannot travel through outer space because they: (UHS MDCAT 2025)

  1. have low speed in vacuum
  2. disperse in space due to long wavelength
  3. lose frequency in the absence of air
  4. lose transmission without interacting particles
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Correct answer: (d) lose transmission without interacting particles

A mechanical wave is carried by the particles of a medium, and space has none to pass it on.

62.What is the necessary condition of a wave motion? (KMU MDCAT 2025)

  1. The medium must be elastic
  2. The medium must be inelastic
  3. The particles of the medium must be independent of each other
  4. The particles of the medium must not be dependent on each other
Show answer

Correct answer: (a) The medium must be elastic

A wave passes on because each displaced particle is pulled back and pulls its neighbour, which needs an elastic medium.

63.A progressive wave is one which: (KMU MDCAT 2025)

  1. Does not vibrate the medium
  2. Carries energy across the medium
  3. Propagates only through air
  4. Requires a denser medium for propagation
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Correct answer: (b) Carries energy across the medium

A progressive wave carries energy forward through the medium without carrying the medium with it.

64.In progressive waves, energy is transferred from one point to another through: (SZABMU MDCAT 2025)

  1. Circular motion of particles
  2. Oscillatory motion of particles
  3. Rotation of particles
  4. Translation of particles
Show answer

Correct answer: (b) Oscillatory motion of particles

Each particle oscillates about its own place and hands the energy on to the next.

65.The waves among the following which require a material medium for their propagation are: (SZABMU MDCAT 2025)

  1. Gamma rays
  2. X-rays
  3. Infrared waves
  4. Infrasonic waves
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Correct answer: (d) Infrasonic waves

Infrasonic waves are sound, and sound needs a medium; the other three are electromagnetic.

66.A wave has velocity 300m/s and frequency 100Hz. If the medium is changed so that velocity doubles but frequency remains constant, the new wavelength will be: (KMU MDCAT 2025)

  1. Halved
  2. Doubled
  3. Same
  4. Zero
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Correct answer: (b) Doubled

With the frequency fixed, $\lambda=v/f$ doubles when the speed doubles.

67.If 20 waves pass a point in 2 seconds and with a speed of 5m/s, then the wavelength of wave is: (SZABMU MDCAT 2025)

  1. 0.5 m
  2. 1 m
  3. 1.5 m
  4. 2 m
Show answer

Correct answer: (a) 0.5 m

Twenty waves in two seconds is $10\,\mathrm{Hz}$, and $\lambda=v/f=5/10$ is $0.5\,\mathrm{m}$.

68.A longitudinal wave has a frequency of 500 Hz and wavelength of 0.6 m, its speed is: (SZABMU MDCAT 2025)

  1. 30 m/s
  2. 83 m/s
  3. 300 m/s
  4. 1200 m/s
Show answer

Correct answer: (c) 300 m/s

$v=f\lambda=500\times0.6$, which is $300\,\mathrm{m\,s^{-1}}$.

69.The motion of transverse waves involves particle's vibration: (SIBA MDCAT 2025)

  1. Along the wave direction
  2. Opposite to energy flow
  3. Perpendicular to wave propagation
  4. In random direction at every point
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Correct answer: (c) Perpendicular to wave propagation

In a transverse wave the particles move at right angles to the direction the wave travels.

70.Newton's original formula underestimated speed of sound in air because he: (SIBA MDCAT 2025)

  1. Ignored viscosity
  2. Assumed isothermal
  3. Considered vacuum conditions
  4. Assumed adiabatic
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Correct answer: (b) Assumed isothermal

Newton took the compressions to be isothermal; Laplace corrected them to adiabatic and got the right speed.

71.The option that shows the conditions used by Laplace for connecting the velocity of sound is options medium used thermodynamics process 1 solid adiabatic 2 liquids isobaric 3 gas adiabatic 4 gas isothermal (SZABMU MDCAT 2025)

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

Correct answer: (c) 3

Laplace took the compressions and rarefactions in a gas to be too quick for heat to escape, that is adiabatic.

72.Speed of sound in air increases with: (KMU MDCAT 2025)

  1. Higher temperature, higher humidity
  2. Lower temperature, lower humidity
  3. Higher pressure at constant temperature
  4. Higher density at constant elasticity
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Correct answer: (a) Higher temperature, higher humidity

Sound travels faster in warmer air, and water vapour is lighter than the air it displaces, so humidity helps too.

73.If the speed of sound is measured at sea level and at the top of a mountain, both at the same temperature, it will be: (SZABMU MDCAT 2025)

  1. Greater at sea level
  2. Greater at the mountain top
  3. The same at both places
  4. Greater where the air is denser
Show answer

Correct answer: (c) The same at both places

The speed of sound depends on the temperature of the air, not on its pressure or density.

74.If two speakers emit sound at same frequency and phase, maximum loudness occurs when: (UHS MDCAT 2025)

  1. Path difference = √2
  2. Path difference = λ
  3. Path difference = λ/4
  4. Path difference = 3λ/43
Show answer

Correct answer: (b) Path difference = λ

Constructive interference needs a path difference of a whole number of wavelengths.

75.Two waves identical traveling in the same medium are superposed: (NUMS MDCAT 2025)

  1. Interference
  2. Diffraction
  3. Reflection
  4. Refraction
Show answer

Correct answer: (a) Interference

Two waves of the same kind crossing in one medium add displacement to displacement, which is interference.

76.The path difference between two sound waves coming from a coherent source of wavelength 50 cm at a point is 100 cm. The superposition of the waves at that point produces: (SIBA MDCAT 2025)

  1. Beats
  2. Echo
  3. Loudness
  4. Silence
Show answer

Correct answer: (c) Loudness

A path difference of $100\,\mathrm{cm}$ is exactly two wavelengths, so the waves arrive in step and reinforce.

77.The phenomenon of interference of sound waves requires: (SIBA MDCAT 2025)

  1. Two sources with different frequencies
  2. Two coherent sources
  3. A single source
  4. A single source and a reflecting surface
Show answer

Correct answer: (b) Two coherent sources

A steady pattern needs two sources of the same frequency holding a constant phase relation.

78.When two identical waves arrive in phase at same point and in a region at the same time the resultant displacement is equal to (SZABMU MDCAT 2025)

  1. Displacement of a single wave
  2. Difference of their displacements
  3. Sum of their displacements
  4. Product of their displacements
Show answer

Correct answer: (c) Sum of their displacements

Waves in step add displacement to displacement, which is constructive interference.

79.In a stationary wave the point that undergoes zero acceleration is: (SZABMU MDCAT 2025)

  1. Node
  2. Antinode
  3. Midpoint between node and antinode
  4. Every point along the wave
Show answer

Correct answer: (a) Node

A node never moves, so its displacement, velocity and acceleration are all zero.

80.Stationary waves are formed in a stretched string of 2m length, such that two vibrating loops are formed. The distance between consecutive nodes formed is: (SZABMU MDCAT 2025)

  1. 0.5 m
  2. 1 m
  3. 2 m
  4. 3 m
Show answer

Correct answer: (b) 1 m

Two loops in $2\,\mathrm{m}$ make each loop $1\,\mathrm{m}$, and a loop runs from one node to the next.

81.The energy of a Simple Harmonic oscillation depends upon the: (UHS MDCAT 2025)

  1. frequency
  2. time period
  3. wavelength
  4. amplitude
Show answer

Correct answer: (d) amplitude

The total energy of an oscillator is $\tfrac12 k x_0^2$, which depends on the amplitude alone.

82.When a particle executing simple harmonic motion moves from the mean position to the extreme position, its kinetic energy: (KMU MDCAT 2025)

  1. Increases continuously
  2. Decreases continuously and becomes zero at the extreme position
  3. Remains constant throughout the motion
  4. Becomes maximum at the extreme position
Show answer

Correct answer: (b) Decreases continuously and becomes zero at the extreme position

The speed falls to zero at the extreme position, and with it the kinetic energy.

83.A particle is moving in a uniform circular path whose projection is executing simple harmonic motion on horizontal diameter. The ratio of instantaneous velocity to the maximum velocity of the projection while passing through the center is: (SZABMU MDCAT 2025)

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

Correct answer: (a) 1 : 1

The projection is fastest as it passes the centre, so the instantaneous speed there is the maximum speed.

Thermodynamics

84.Heat will spontaneously flow from: (KMU MDCAT 2025)

  1. Lower to higher internal energy only
  2. High pressure to low pressure
  3. High to low temperature
  4. Low temperature to high temperature
Show answer

Correct answer: (c) High to low temperature

Heat of itself passes only from the hotter body to the colder one.

85.During rubbing of hands, internal energy: (NUMS MDCAT 2025)

  1. Increases
  2. Decreases
  3. Zero
  4. Remains same
Show answer

Correct answer: (a) Increases

Friction turns the work of rubbing into internal energy, so the hands warm.

86.During the drilling of a metal surface the drill bit heats up. This heat comes from the: (SIBA MDCAT 2025)

  1. Vibration of the tool
  2. Work done against friction
  3. Flow of electric current
  4. Compression of air
Show answer

Correct answer: (b) Work done against friction

The work done against friction is turned into internal energy, which raises the temperature of the bit.

87.When thermal energy is transferred from a hot object to a cold one, the change occurs in the hot object as: (SZABMU MDCAT 2025)

  1. Increases in internal energy
  2. Decrease in internal energy
  3. Increase in temperature
  4. Increase in heat content
Show answer

Correct answer: (b) Decrease in internal energy

The hot body gives up heat, so its internal energy falls.

88.Bursting of tire is an example of which process? (NUMS MDCAT 2025)

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

Correct answer: (a) Adiabatic

The air escapes too fast for any heat to be exchanged, so the expansion is adiabatic.

89.A gas expands from 1 m^3 to 3 m^3 at constant pressure of 2 Pa. Work done is: (SIBA MDCAT 2025)

  1. 2J
  2. 4J
  3. 6J
  4. 8J
Show answer

Correct answer: (b) 4J

$W=P\Delta V=2\times2$, which is $4\,\mathrm{J}$.

90.According to First law of thermodynamics when heat flows into a system and no work is done the internal energy of the system must (UHS MDCAT 2025)

  1. Increase
  2. Decrease
  3. Remains constant
  4. Becomes zero
Show answer

Correct answer: (a) Increase

With no work done, all the heat taken in goes into the internal energy, which therefore rises.

91.Which of the following has highest specific heat capacity? (NUMS MDCAT 2025)

  1. Copper
  2. Iron
  3. Water
  4. Glass
Show answer

Correct answer: (c) Water

Water has an unusually high specific heat, about $4200\,\mathrm{J\,kg^{-1}\,K^{-1}}$.

92.At a constant Pressure (Cp) and Volume (Cv), an ideal gas has C p - C v = R Then Cp will be? (KMU MDCAT 2025)

  1. R/2
  2. 3/2 R
  3. 5/2 R
  4. 7/2 R
Show answer

Correct answer: (c) 5/2 R

For a monatomic ideal gas $C_v=\tfrac32R$, so $C_p=C_v+R=\tfrac52R$.

Electrostatics

93.If a plastic sheet of relative permittivity 2.5 is inserted between two-point charges placed in vacuum, then the electrostatic force between them: (UHS MDCAT 2025)

  1. Increases by a factor of 2.5
  2. Decreases by a factor of 2.5
  3. Increases by a factor of 5
  4. Decreases by a factor of 5
Show answer

Correct answer: (b) Decreases by a factor of 2.5

The medium divides the force by its relative permittivity, so the force falls to $1/2.5$ of its value.

94.If the distance between two charges is halved and magnitude of charges are also doubled, then the force between these charges becomes: (UHS MDCAT 2025)

  1. two times
  2. four times
  3. eight times
  4. sixteen times
Show answer

Correct answer: (d) sixteen times

Doubling both charges multiplies the force by four, and halving the separation by four again.

95.Coulomb's law fits well into: (KMU MDCAT 2025)

  1. Newton's 1st law
  2. Newton's 2nd law
  3. Newton's 3rd law
  4. Gauss's law
Show answer

Correct answer: (c) Newton's 3rd law

The two charges push or pull each other equally and oppositely, which is the third law.

96.The force between two charges is 28 N in vacuum. If paraffin wax of relative permittivity 2.8 is introduced between the charges as a medium, then the force reduces to: (SIBA MDCAT 2025)

  1. 25 N
  2. 20 N
  3. 15 N
  4. 10 N
Show answer

Correct answer: (d) 10 N

The medium divides the force by its relative permittivity, and $28/2.8$ is $10\,\mathrm{N}$.

97.Two equal charges experience a certain force when placed in vacuum. When the charges are placed in a medium, the force becomes 1/4th. The dielectric constant of the medium is: (SZABMU MDCAT 2025)

  1. 0.25
  2. 2
  3. 4
  4. 16
Show answer

Correct answer: (c) 4

The medium divides the force by its dielectric constant, so a quarter of the force means a constant of four.

98.The electric field at a point due to two equal and opposite charges is 100 N/C. If the magnitude of each charge is doubled then the electric field at that point becomes: (UHS MDCAT 2025)

  1. 50 N/C
  2. 100 N/C
  3. 200 N/C
  4. 400 N/C
Show answer

Correct answer: (c) 200 N/C

The field of each charge is proportional to that charge, so doubling both doubles the resultant.

99.For two equal positive charges, the electric field weakest? (UHS MDCAT 2025)

  1. Midway between them
  2. Along the perpendicular bisector
  3. Close to either charge
  4. At infinity
Show answer

Correct answer: (a) Midway between them

Midway between two equal positive charges the two fields are equal and opposite, so they cancel.

100.The electric field at a point is defined as: (KMU MDCAT 2025)

  1. Potential per unit charge
  2. Work done per unit time
  3. Charge per unit area
  4. Force per unit positive test charge
Show answer

Correct answer: (d) Force per unit positive test charge

Field intensity is the force per unit positive charge placed at the point.

101.The point where the electric field is zero between two opposite charge lies: (SIBA MDCAT 2025)

  1. Closer to the positive charge
  2. At the mid-point
  3. Closer to the negative charge
  4. Nowhere between them
Show answer

Correct answer: (d) Nowhere between them

Between unlike charges both fields point the same way, so they add and never cancel.

102.A point lies 3m from a +5µC charge and 4m from a -3µC charge. The most appropriate direction of the net electric field at this point is directed: (SIBA MDCAT 2025)

  1. Away from +5µC charge
  2. Towards +5µC charge
  3. Away from the -3µC charge
  4. Perpendicular to the line joining the charges
Show answer

Correct answer: (a) Away from +5µC charge

The nearer and larger charge gives much the stronger field, so the resultant points away from it.

103.The electric field at a point due to a point charge is 200N/C. If suppose a -4C test charge is placed at that point then the magnitude of electric field and electric force on it is: (SIBA MDCAT 2025)

  1. 200N/C and 50N
  2. 200N/C and 200N
  3. 200N/C and 800N
  4. 800N/C and 800N
Show answer

Correct answer: (c) 200N/C and 800N

The field is a property of the source, so it stays $200\,\mathrm{N\,C^{-1}}$, and $F=qE=4\times200$ is $800\,\mathrm{N}$.

104.If a test charge of magnitude 2C experience forces of 100N and 200N at two points A and B in an electric field respectively. The ratio of electric fields at A to that of B is: (SZABMU MDCAT 2025)

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

Correct answer: (b) 1:2

The field is $F/q$ with the same $q$, so the ratio of fields is the ratio of forces, $1:2$.

105.If the surface charge density of an infinite sheet increases by 25%, the electric field intensity: (UHS MDCAT 2025)

  1. Increases by 25%
  2. Increases by 50%
  3. Decreases by 25%
  4. Remains the same
Show answer

Correct answer: (a) Increases by 25%

The field of an infinite sheet is proportional to the surface charge density, so it rises in the same proportion.

106.Electric field intensity of infinite charge sheet: (NUMS MDCAT 2025)

  1. E = 2σ/ε0
  2. E = 1/ε0
  3. E = σ/ε0
  4. σ/(2ε0)
Show answer

Correct answer: (d) σ/(2ε0)

The field of an infinite sheet is $\sigma/2\varepsilon_0$ and does not fall off with distance.

107.The work done in moving a unit positive charge from one point to another while keeping the charge in electrostatic equilibrium is called: (KMU MDCAT 2025)

  1. Kinetic energy
  2. Potential energy
  3. Elastic potential energy
  4. Potential difference
Show answer

Correct answer: (d) Potential difference

The work per unit charge in carrying it between two points is the potential difference.

108.The electric potential at a point due to a point charge is 100J/C. If a test charge of magnitude 1C placed at that point is replaced with a 2C charge, then the physical quantity that will change is: (SZABMU MDCAT 2025)

  1. Electric Field at that point
  2. Electric potential at that point
  3. Electric Potential Energy of the system
  4. Temperature
Show answer

Correct answer: (c) Electric Potential Energy of the system

The potential belongs to the source charge, but the energy $qV$ of the charge placed there doubles with $q$.

109.The electric potential at a distance r is given by the formula: (NUMS MDCAT 2025)

  1. V = kq/r
  2. 1/4πε0qr
  3. Ed
  4. Ir
Show answer

Correct answer: (a) V = kq/r

The potential of a point charge at a distance $r$ is $kq/r$.

110.The energy stored in a capacitor is: (NUMS MDCAT 2025)

  1. QV
  2. QV/2
  3. Q2V
  4. 2QV
Show answer

Correct answer: (b) QV/2

The charge builds up as the voltage rises, so the stored energy is $\tfrac12QV$, not $QV$.

111.The unit of RC in case of charging a capacitor is: (SZABMU MDCAT 2025)

  1. Farad
  2. Seconds
  3. Ohm
  4. Volt
Show answer

Correct answer: (b) Seconds

Ohms times farads give seconds, which is why $RC$ is called the time constant.

Current Electricity

112.If the potential difference (V) across a conductor is doubled, keeping resistance (R) constant, the power dissipated (P) becomes: (KMU MDCAT 2025)

  1. Doubled
  2. Halved
  3. Four times
  4. Remains unchanged
Show answer

Correct answer: (c) Four times

$P=V^2/R$, so twice the voltage across the same resistance dissipates four times the power.

113.If voltage across a resistor is doubled then its resistance will become: (temperature and physical state of the conductor remains constant). (SZABMU MDCAT 2025)

  1. Doubled
  2. Half
  3. Four times
  4. Remains constant
Show answer

Correct answer: (d) Remains constant

Resistance is a property of the conductor, so it is unchanged; the current doubles instead.

114.High slope of Ohm's law graph means (SZABMU MDCAT 2025)

  1. Low resistance
  2. High resistance
  3. Open circuit
  4. Low current
Show answer

Correct answer: (a) Low resistance

On a graph of current against potential difference the slope is $1/R$, so a steep line means a small resistance.

115.What will potential difference, if a wire has resistance of 10Ω and current 2A flow through it : (SZABMU MDCAT 2025)

  1. 5V
  2. 10V
  3. 20V
  4. 40V
Show answer

Correct answer: (c) 20V

$V=IR=2\times10$, which is $20\,\mathrm{V}$.

116.The reciprocal of the resistivity of a material is called its: (UHS MDCAT 2025)

  1. impedance
  2. conductivity
  3. admittance
  4. reactance
Show answer

Correct answer: (b) conductivity

Conductivity is the reciprocal of resistivity.

117.If the length of the conductor is made 4 times its original length, its resistance becomes (UHS MDCAT 2025)

  1. quarter
  2. half
  3. zero
  4. 4 times
Show answer

Correct answer: (d) 4 times

Resistance is proportional to length, so four times the length is four times the resistance.

118.The unit of temperature coefficient of resistivity is (UHS MDCAT 2025)

  1. 1/C
  2. 1/K
  3. 1/A
  4. 1/Ω
Show answer

Correct answer: (b) 1/K

It is a fractional change in resistivity per degree, so its unit is the reciprocal kelvin.

119.Conductance is reciprocal of resistance, its unit is: (NUMS MDCAT 2025)

  1. Siemen
  2. Ohm
  3. Ampere
  4. Watt
Show answer

Correct answer: (a) Siemen

Conductance is the reciprocal of resistance and is measured in siemens.

120.The fraction change in resistance per kelvin is: (NUMS MDCAT 2025)

  1. Coefficient of conductivity
  2. Temperature coefficient of resistance
  3. Coefficient of conductance
  4. Coefficient of resistivity
Show answer

Correct answer: (b) Temperature coefficient of resistance

That fraction is the temperature coefficient of resistance.

121.The value of temperature co-efficient of a conductor is zero. This indicates that with the rise in temperature, resistance of conductor: (SIBA MDCAT 2025)

  1. Increases
  2. Decreases
  3. Remain same
  4. Becomes zero
Show answer

Correct answer: (c) Remain same

A zero coefficient means the resistance does not change with temperature at all.

122.Terminal voltage of a cell equals its EMF only when: (UHS MDCAT 2025)

  1. No current flows
  2. Current is maximum
  3. Internal resistance is infinite
  4. Load resistance is zero
Show answer

Correct answer: (a) No current flows

With no current there is no drop across the internal resistance, so the terminals read the full emf.

123.Internal resistance reduces the terminal voltage because it: (SIBA MDCAT 2025)

  1. Produces back emf
  2. Causes power loss inside the battery
  3. Increases the current
  4. Decreases the emf
Show answer

Correct answer: (b) Causes power loss inside the battery

Some of the emf is spent driving the current through the cell itself, and that part appears as heat inside it.

124.A high internal resistance battery is not suitable for heavy loads due to: (SZABMU MDCAT 2025)

  1. Excess voltage drop
  2. High terminal voltage
  3. Infinite emf
  4. Constant current
Show answer

Correct answer: (a) Excess voltage drop

A heavy load draws a large current, and the drop inside the cell then leaves little at the terminals.

Electromagnetism

125.The SI unit of magnetic flux is: (NUMS MDCAT 2025)

  1. Tesla
  2. Weber
  3. Henry
  4. Farad
Show answer

Correct answer: (b) Weber

Magnetic flux is measured in webers, one weber being a tesla square metre.

126.The magnetic flux through a loop of 1m^2 in a 0.5T magnetic field is same as magnetic flux through a loop of 0.5 m^2 in a magnetic field of: (SIBA MDCAT 2025)

  1. 1.0 T at 0°
  2. 1.0 T at 60°
  3. 2.0 T at 90°
  4. 0.5 T at 90°
Show answer

Correct answer: (a) 1.0 T at 0°

Flux is $BA\cos\theta$, so $0.5\,\mathrm{m^2}$ facing a $1.0\,\mathrm{T}$ field square on gives the same $0.5\,\mathrm{Wb}$.

127.Magnetic force acting on a charge at rest is: (NUMS MDCAT 2025)

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

Correct answer: (a) Zero

The force is $qvB\sin\theta$, and a charge at rest has no velocity, so there is no force.

128.An electron is projected along the positive x-axis in a magnetic field lying in xz-plane. The magnetic force on the electron will act along the: (SIBA MDCAT 2025)

  1. x-axis
  2. -x-axis
  3. y-axis
  4. -y-axis
Show answer

Correct answer: (c) y-axis

The force is along $qv\times B$, and with the velocity along x and the field in the xz plane the product lies along y.

129.The path of a charged particle in a plane perpendicular to a uniform magnetic field is: (NUMS MDCAT 2025)

  1. Circular
  2. Helical
  3. Parabola
  4. Elliptical
Show answer

Correct answer: (a) Circular

With the velocity always at right angles to the field, the magnetic force is centripetal and the path is a circle.

130.If mass of a charged particle is doubled, cyclotron frequency becomes: (NUMS MDCAT 2025)

  1. Doubled
  2. Halved
  3. Quadrupled
  4. One fourth
Show answer

Correct answer: (b) Halved

The cyclotron frequency is $qB/2\pi m$, so twice the mass halves it.

Electromagnetic Induction

131.Basic requirement for induced emf is: (NUMS MDCAT 2025)

  1. Flux linked to coil
  2. No flux linked to coil
  3. Coil should be circular
  4. Change in flux links to the coil
Show answer

Correct answer: (d) Change in flux links to the coil

An emf appears only while the flux through the coil is changing.

132.EMF induced is zero when plane of coil is: (NUMS MDCAT 2025)

  1. Perpendicular to B
  2. Parallel to B
  3. Antiparallel
  4. None of these
Show answer

Correct answer: (a) Perpendicular to B

With the plane perpendicular to the field the flux is already at its maximum, so it is momentarily not changing.

133.A loop moves toward a stationary magnet. The induced current will: (UHS MDCAT 2025)

  1. enhance the motion
  2. try to stop the approach
  3. become zero
  4. become alternating
Show answer

Correct answer: (b) try to stop the approach

By Lenz’s law the induced current opposes the change that made it, so it opposes the approach.

134.According to Lenz's Law, the direction of induced current in a conductor is such that it: (KMU MDCAT 2025)

  1. Opposes the change in magnetic flux
  2. Enhances the change in magnetic flux
  3. Is perpendicular to the magnetic field
  4. Is parallel to the magnetic field
Show answer

Correct answer: (a) Opposes the change in magnetic flux

The induced current always sets up a flux that opposes the change producing it.

135.A conducting ring is placed near a current-carrying coil. As the current in the coil increases, the induced current in the ring flows: (SZABMU MDCAT 2025)

  1. In the direction of magnetic field
  2. To increases the magnetic flux
  3. To oppose increasing magnetic flux
  4. Randomly without a definite direction
Show answer

Correct answer: (c) To oppose increasing magnetic flux

By Lenz’s law the ring drives a current whose own flux opposes the rise.

136.In an ideal transformer, if the primary voltage is doubled and the turns ratio remains the same, what happens to the secondary current? (UHS MDCAT 2025)

  1. Doubles
  2. Halves
  3. Remains the same
  4. Becomes four times
Show answer

Correct answer: (a) Doubles

The turns ratio doubles the secondary voltage too, and across the same load that doubles the secondary current.

137.In a step-up transformer, if the secondary voltage is increased by a factor of 10, the current in secondary coil will be: (SIBA MDCAT 2025)

  1. 10 times higher than the primary current
  2. 10 times lower than the primary current
  3. Equal to the primary current
  4. One-tenth of the primary current in transformer
Show answer

Correct answer: (d) One-tenth of the primary current in transformer

Power is conserved in an ideal transformer, so ten times the voltage means a tenth of the current.

Alternating Current

138.A phase difference of 90° is equal to: (UHS MDCAT 2025)

  1. π radians
  2. π/2 radians
  3. 2π radians
  4. π/4 radians
Show answer

Correct answer: (b) π/2 radians

A full cycle is $2\pi$ radians, so a quarter of it is $\pi/2$.

139.In a pure capacitance AC circuit, the current: (KMU MDCAT 2025)

  1. Lags behind voltage by 90°
  2. Leads the voltage by 90°
  3. Is in phase with the voltage
  4. Leads the voltage by 45°
Show answer

Correct answer: (b) Leads the voltage by 90°

A capacitor must be charged before a voltage appears across it, so the current runs a quarter cycle ahead.

140.If frequency of AC is doubled, the inductive reactance will: (SIBA MDCAT 2025)

  1. Remain same
  2. Be halved
  3. Be doubled
  4. Become zero
Show answer

Correct answer: (c) Be doubled

Inductive reactance is $2\pi fL$, so it is proportional to the frequency.

141.A capacitor is connected to an AC source. If the frequency of the AC source is doubled the current in a purely capacitive circuit will: (SZABMU MDCAT 2025)

  1. Be doubled
  2. Remains Unchanged
  3. Become Half
  4. Becomes zero
Show answer

Correct answer: (a) Be doubled

Capacitive reactance is $1/2\pi fC$, so twice the frequency halves it and doubles the current.

142.The wave that has the highest frequency & penetrating power is: (UHS MDCAT 2025)

  1. X-rays
  2. Ultraviolet rays
  3. Gamma rays
  4. Microwaves
Show answer

Correct answer: (c) Gamma rays

Gamma rays sit at the top of the electromagnetic spectrum in frequency and penetrate the most.

Electronics

143.Which of the following act as a semiconductor? (NUMS MDCAT 2025)

  1. Iron
  2. Silicon
  3. Zinc
  4. Tungsten
Show answer

Correct answer: (b) Silicon

Silicon is the tetravalent element of which most semiconductor devices are made.

144.The current in forward biased PN junction is mainly due to: (SZABMU MDCAT 2025)

  1. Majority carriers
  2. Minority carriers
  3. leakage carrier
  4. Thermionic emission
Show answer

Correct answer: (a) Majority carriers

Forward bias narrows the barrier, so the majority carriers cross in numbers.

145.In a full-wave rectifier using two diodes, the diodes: (KMU MDCAT 2025)

  1. D1 and D2 operate:
  2. Simultaneously during both half-cycles
  3. In alternate switching mode
  4. Only when both ends of transformer are positive
Show answer

Correct answer: (c) In alternate switching mode

Each diode conducts on the half cycle that makes its end of the secondary positive, so they take turns.

146.The process of converting AC into pulsating DC is called: (NUMS MDCAT 2025)

  1. Amplification
  2. Modulation
  3. Rectification
  4. Filtration
Show answer

Correct answer: (c) Rectification

Rectification is the conversion of alternating current into a direct current that flows one way only.

Dawn of Modern Physics

147.The energy of a quantum is given by which equation? (KMU MDCAT 2025)

  1. E = mc^2
  2. E = hf
  3. E = 1/2 mv^2
  4. E = qV
Show answer

Correct answer: (b) E = hf

Planck’s relation gives the energy of one quantum as $E=hf$.

148.In photoelectric effect, stopping potential depends upon: (NUMS MDCAT 2025)

  1. Intensity of light
  2. Frequency of light
  3. Speed of light
  4. Amplitude of light
Show answer

Correct answer: (b) Frequency of light

The stopping potential measures the maximum kinetic energy, which depends on the frequency alone.

149.If different colored light beams have same total energy, which color beam will contain the smallest number of photons? (SZABMU MDCAT 2025)

  1. Violet
  2. Blue
  3. Green
  4. Red
Show answer

Correct answer: (a) Violet

Violet photons carry the most energy each, so the fewest of them are needed to make up the same total.

150.According to the particle model of light, a photon is: (SZABMU MDCAT 2025)

  1. A particle with mass and charge
  2. A quantum of energy with zero rest mass and zero charge
  3. A continuous energy wave
  4. A particle that travels slower than light
Show answer

Correct answer: (b) A quantum of energy with zero rest mass and zero charge

A photon is a packet of energy with no rest mass and no charge.

Atomic Spectra

151.The Balmer series of hydrogen spectrum appears in the (UHS MDCAT 2025)

  1. Infrared region
  2. Ultraviolet region
  3. X-ray region
  4. Visible region
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Correct answer: (d) Visible region

The Balmer lines end on the second level and fall in the visible part of the spectrum.

152.In hydrogen spectrum, the Brackett series lies in (KMU MDCAT 2025)

  1. Ultraviolet region
  2. Visible region
  3. Infrared region
  4. X ray region
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Correct answer: (c) Infrared region

The Brackett lines end on the fourth level, and their photons fall in the infrared.

153.Which of the following spectrum is produced when atoms are in the gaseous state? (NUMS MDCAT 2025)

  1. Continuous spectrum
  2. Band spectrum
  3. Line spectrum
  4. Absorption spectrum
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Correct answer: (c) Line spectrum

Free atoms of a gas emit at sharply defined frequencies, so the spectrum is a set of lines.

154.Quantized momentum was explained by: (NUMS MDCAT 2025)

  1. Einstein
  2. Bohr
  3. de-Broglie
  4. Rutherford
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Correct answer: (b) Bohr

Bohr postulated that the angular momentum of the orbiting electron is a whole multiple of $h/2\pi$.

155.The spectra obtained by absorption or emission of radiation by atoms of the gas: (NUMS MDCAT 2025)

  1. Atomic spectra
  2. Molecular spectra
  3. Band spectra
  4. Continuous spectra
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Correct answer: (a) Atomic spectra

Spectra given out or taken up by free atoms are atomic spectra.

156.Two spectral lines in the Hydrogen atom spectrum are close together. This likely means: (SZABMU MDCAT 2025)

  1. The energy difference is zero
  2. The energy difference is small
  3. The light intensity is low
  4. The atom become unstable
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Correct answer: (b) The energy difference is small

Photon energy sets the frequency, so lines close together come from levels close in energy.

Nuclear Physics

157.The protons in the nucleus of an atom DO NOT exit due to (UHS MDCAT 2025)

  1. Electromagnetic force
  2. Gravitational Force
  3. Weak Nuclear Force
  4. Strong Nuclear Force
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Correct answer: (b) Gravitational Force

Gravitation between protons is far too feeble to matter; it is the strong nuclear force that holds them.

158.Stability of radioactivity element is determined by: (NUMS MDCAT 2025)

  1. Decay constant
  2. Rate of the radioactive decay
  3. Time of decay
  4. Number of radioactive nuclei
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Correct answer: (a) Decay constant

The decay constant is the probability of decay per second, so the smaller it is the more stable the nuclide.

159.After 3 half-lives, the remaining fraction of a radioactive sample is: (UHS MDCAT 2025)

  1. 1/2
  2. 1/4
  3. 1/8
  4. 1/16
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Correct answer: (c) 1/8

Each half life halves what is left, so after three of them $1/8$ remains.

160.The time in which half of the given number of radioactive nuclei decay is known as (UHS MDCAT 2025)

  1. 1/2 life of radioactive element.
  2. 2/3 life of radioactive element.
  3. 1/4 life of radioactive element.
  4. 2/5 life of radioactive element.
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Correct answer: (a) 1/2 life of radioactive element.

That time is the half life of the element.

161.Half-life of a radioactive element is 10 days. After 30 days, fraction remaining is: (NUMS MDCAT 2025)

  1. 1/2
  2. 1/4
  3. 1/8
  4. 1/16
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Correct answer: (c) 1/8

Thirty days is three half lives, and each halves what is left, so $1/8$ remains.

Other MDCAT past papers