Free Electronics MCQs with Answers
660 Electronics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
A p-n junction forms when p-type and n-type semiconductor regions meet, creating a depletion layer, barrier potential and rectifying action. The work covers forward and reverse bias, junction current, diode characteristics, and how a diode converts alternating current into pulsating direct current through half-wave and full-wave rectification.
Last updated
Read the Electronics notesFree MDCAT chapter notes with key terms660 questions · page 15 of 33
- A. Step up
- B. Step down
- C. Equalize
- D. None of these options is correct
Explanation: In half wave rectifier, we generally use a step-down transformer because the voltage needed for the diode is very small.
Correct answer: Step down- A. 358.98 mW
- B. 275.2 mW
- C. 145.76 mW
- D. 456.78 mW
Explanation: A.c power input = Irms^2 (RF+Rr) Irms = Imax/ √2 = Vmax/ (Rf+Rr) √2 [ as V=IR and I=V/R] = 30/ (1500+10) *1.414 = 13.5 mASo, power input =…
Correct answer: 275.2 mW- A. Half wave rectifier
- B. Full wave rectifier
- C. Bridge rectifier
- D. None of them
Explanation: Bridge rectifiers are widely used for large appliances, which can convert high AC voltage to low DC voltage.
Correct answer: Bridge rectifier- A. 358.98 mW
- B. 275.2 mW
- C. 145.76 mW
- D. 456.78 mW
Explanation: The AC P(in)=Irms^2(RF+Rr).Irms=Vm/(Rf+RL)√2=30/(1500+10) x 1.414=13.5mASo, P(in)=(13.5 x 10^-3)^2 x (1500+10)=275.2mW.
Correct answer: 275.2 mW- A. Reverse biased
- B. Forward biased
- C. Potential barrier
- D. None of these options are correct
Explanation: During the positive half cycle of the AC voltage, the diode will be forward biased and the current flows through the diode.
Correct answer: Reverse biased- A. 1.21
- B. 0.6
- C. 0.482
- D. 0.9
Explanation: The ripple factor for a full-wave rectifier is 0.482 which can also be written as 48.2%.
Correct answer: 0.482- A. 4
- B. 3
- C. 2
- D. 5
Explanation: Bridge rectifiers use four diodes that are arranged cleverly to convert the AC supply voltage to a DC supply voltage.
Correct answer: 4288. A full-wave rectifier is operating from 50 Hz. The fundamental frequency of the ripple will be:
- A. 100 Hz
- B. 25 Hz
- C. 50 Hz
- D. 200 Hz
Explanation: A full-wave rectifier rectifies both the half cycles of the AC input meaning it conducts twice during a cycle.
Correct answer: 100 Hz- A. 1
- B. 2
- C. 3
- D. 4
Explanation: RECTIFICATION:The conversion of AC into DC is called rectification.RECTIFIER:A device used for rectification is called a…
Correct answer: 1- A. 5
- B. 4
- C. 3
- D. 2
Explanation: RECTIFICATION:The conversion of AC into DC is called rectification.RECTIFIER:A device used for rectification is called a…
Correct answer: 4- A. AC to DC
- B. DC to AC
- C. AC to triangular current
- D. DC to triangular current
Explanation: A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC)…
Correct answer: AC to DC- A. It needs much smaller transformer for the same output
- B. No center tap required
- C. Less PIV rating per diode
- D. All of the above
Explanation: Options A, B and C all are individually correct. So, we will choose option D i.e. all options are correct.
Correct answer: All of the above- A. lrms / Vrms
- B. ldc / lrms
- C. lrms / Idc
- D. lrms +Idc
Explanation: Option A : Ripple factor is not defined as Irms / Vrms. Option B : Ripple factor is not defined as Idc/Irms.Option : C The ripple factor…
Correct answer: lrms / Idc- A. 25
- B. 50
- C. 100
- D. 75
Explanation: Option A : The number of pulses is 50 not 25.Option: B Rectifiers produce unidirectional and pulsating voltage from an A.C.
Correct answer: 50- A. Modulation
- B. Amplification
- C. Ossilation
- D. Rectification
Explanation: Rectification is the conversion of alternating current (AC) to direct current (DC).
Correct answer: Rectification- A. 0V
- B. 14.4V
- C. 28.3V
- D. 56.6V
Explanation: Vm = 40V Vrms = (Vm /√2) = (40 / √2) = 28.28V ∴ To get Vm of 40V at the output, Vrms of secondary voltage has to be 28.28V
Correct answer: 28.3V- A. Step up
- B. Step down
- C. Equalize
- D. None of them
Explanation: In a half-wave rectifier, we generally use a step-down transformer because the voltage needed for the diode is very small.
Correct answer: Step down- A. Lower-half cycle
- B. Upper half cycle
- C. Both cycles
- D. None of these
Explanation: Full-wave rectification rectifies the negative component of the input voltage to a positive voltage, then converts it into DC (pulse…
Correct answer: Both cycles- A. 1
- B. 3
- C. 2
- D. 4
Explanation: Only one diode is needed in the half-wave rectifier. This diode limits the current flow in one direction, which means that only half of…
Correct answer: 1- A. Vm
- B. Vm/√2
- C. 2Vm
- D. Vm/3
Explanation: A full-wave rectifier is defined as a rectifier that converts the complete cycle of alternating current into pulsating direct current…
Correct answer: 2Vm