Rectification

Rectification MDCAT MCQs with answers

29 past paper MCQs on Rectification, from the Electronics unit of MDCAT Physics. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

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1.The conversion of A.C. into D.C. is called rectification and the circuit is called a rectifier. Which component of electronics acts as a rectifier? (MDCAT 2024)

  1. diode
  2. transistor
  3. transformer
  4. inductor
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Correct answer: (a) diode

A diode conducts in one direction only, which is what rectification needs.

2.Full wave rectification is given by: (MDCAT 2024)

  1. one diode connected in a bridge type arrangement
  2. two diodes connected in a bridge type arrangement
  3. three diodes connected in a bridge type arrangement
  4. four diodes connected in a bridge type arrangement
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Correct answer: (d) four diodes connected in a bridge type arrangement

The bridge rectifier uses four diodes, so both halves of the cycle drive the load the same way.

3.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
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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.

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

  1. Amplification
  2. Modulation
  3. Rectification
  4. Filtration
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Correct answer: (c) Rectification

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

5.The conversion of A.C into D.C is called rectification and circuit is called rectifier. Which component of electronics acts as a rectifier? (UHS MDCAT 2024)

  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.

6.For rectification, transformer used is: (NUMS MDCAT 2024)

  1. With low input voltage
  2. With low input resistance
  3. Step up
  4. Step down
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Correct answer: (d) Step down

A rectifier works on a low voltage, so the mains is stepped down first.

7.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.

8.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.

9.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
Show answer

Correct answer: (a) Diode

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

10.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.

11.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.

12.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.

13.Which of the following rectifier uses wheatstone bridge to rectify signal: (PMC MDCAT 2022)

  1. Half wave
  2. Full wave
  3. Bridge
  4. Both half and full wave
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Correct answer: (c) Bridge

A bridge rectifier is four diodes in a Wheatstone arrangement.

14.Most widely used rectifier is: (PMC MDCAT 2022)

  1. Half wave rectifier
  2. Full wave rectifier
  3. Bridge rectifier
  4. Loop rectifier
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Correct answer: (c) Bridge rectifier

The bridge rectifier needs no centre-tapped transformer, so it is the one usually used.

15.A full wave rectifier passes _________ into positive cycles: (PMC MDCAT 2022)

  1. Lower half cycle
  2. Upper half cycle
  3. Both lower and upper half cycles
  4. One quarter cycle
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Correct answer: (c) Both lower and upper half cycles

A full wave rectifier turns both half cycles the same way up.

16.Ripple factor of half wave rectifier Is: (PMC MDCAT 2022)

  1. 1.21
  2. 0.8
  3. 0.6
  4. 0.4
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Correct answer: (a) 1.21

The ripple factor of a half wave rectifier is $1.21$.

17.Q.72 A device that converts AC into DC is called: (NUMS MDCAT 2022)

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

A diode passes current one way only.

18.Q.73 The conversion of alternating current into direct current is called: (NUMS MDCAT 2022)

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

That process is rectification.

19.Which of the following are component of half wave rectifier? (PMC Practice 2021)

  1. Transformer
  2. Load resistance
  3. Power supply
  4. All of the above
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Correct answer: (d) All of the above

A half wave rectifier is a transformer, a diode and a load resistance fed from the supply.

20.The basic purpose of filter is to? (PMC Practice 2021)

  1. Minimize variation in ac signal
  2. Suppress hannonics in rectified output
  3. Remove ripples from the rectified output
  4. Stabilize dc output voltage
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Correct answer: (c) Remove ripples from the rectified output

A filter smooths the rectified output by charging on the peaks and discharging between them.

21.In which rectifier is the ripple factor less? (PMC Practice 2021)

  1. Full wave
  2. Half wave
  3. Both A and B
  4. None of them
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Correct answer: (a) Full wave

A full wave rectifier uses both half cycles, so its output is far smoother.

22.A full wave rectifier is operating from 50 Hz mains. Fundamental frequency of ripple will be: (PMC Practice 2021)

  1. 100 Hz
  2. 25 Hz
  3. 50 Hz
  4. 200 Hz
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Correct answer: (a) 100 Hz

Both half cycles give a pulse, so the ripple runs at twice the mains frequency.

23.The bridge rectifier is preferred to an ordinary two diode full-wave rectifier because? (PMC Practice 2021)

  1. It needs a much smaller transformer for the same output
  2. No center tap required
  3. Less PIV rating per diode
  4. All of the above options are correct
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Correct answer: (d) All of the above options are correct

It needs no centre tap, uses a smaller transformer and puts a lower reverse voltage on each diode.

24.If a half-wave rectifier is used to convert 50 Hz AC into DC, then the number of pulses present in the rectifier voltage is: (PMC Practice 2021)

  1. 25
  2. 50
  3. 100
  4. 75
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Correct answer: (b) 50

Only one half cycle in each is passed, so there are fifty pulses a second.

25.In a centre tap full-wave rectifier, if Vm is the peak voltage across the secondary coil of a transformer, the maximum voltage across the reverse bias is: (PMC Practice 2021)

  1. Vm
  2. Vm/√2
  3. 2Vm
  4. Vm/3
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Correct answer: (c) 2Vm

The idle diode sees the whole secondary, so it must stand $2V_m$ in reverse.

26.In a full-wave rectification, the number of diodes used are: (PMC MDCAT 2020)

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

A bridge rectifier uses four diodes.

27.PIV stands for : (PMC MDCAT 2020)

  1. Positive inverse voltage
  2. Pawn Bh Integrated voltage
  3. Peak inverse voltage
  4. Peak integrated voltage
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Correct answer: (c) Peak inverse voltage

PIV is the peak inverse voltage a diode must stand when it is not conducting.

28.The direction of current through the load resistance of a full-wave rectification circuit: (UHS MDCAT 2019)

  1. remains constant
  2. inverts for positive cycle
  3. changes for every cycle
  4. inverts for negative cycle
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Correct answer: (a) remains constant

Both half cycles are turned the same way up, so the current through the load never reverses.

29.In case of half wave rectification the resistance of diode during negative half of A.C is: (UHS MDCAT 2018)

  1. Very high
  2. Very low
  3. A few ohms
  4. Negative
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Correct answer: (a) Very high

On the reverse half cycle the diode is reverse biased, so its resistance is enormous.

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