Electrical Online Test 25

Attempt Free Electrical Online Test 25 Here. Read The Important Electrical MCQ From Below.

1) Which rectifier requires four diodes?

a. Half-wave voltage doubler
b. Full-wave voltage doubler
c. Full-wave bridge circuit
d. None of the above
Ans. a. Half-wave voltage doubler

2) Diode transition or space capacitance is due to

a. Majority carrier moves from junction
b. Storage of minority charge
c. Both
d. None of these
Ans. a. Majority carrier moves from junction

3) Which circuit of transistor is known as emitter follower

a. CB
b. CC
c. CE
d. ALL
Ans. b. CC

4) When a diode is forward-biased, the recombination of free electron and holes may produce

a. Heat
b. Light
c. Radiation
d. All of the above
Ans. d. All of the above

Electrical Online Test 25

5) A Zener diode is based on the principle of

a. Thermionic emission
b. Tunneling of charge carriers across the junction
c. Diffusion of charge carriers across the junction
d. None of the above
Ans. b. Tunneling of charge carriers across the junction

6) Silicon diode is less suited for low voltage rectifier operation because

a. Its breakdown voltage is high
b. Its reverse saturation current is low
c. Its cut-in voltage is high
d. None of the above
Ans. c. Its cut-in voltage is high

7) Silicon is not suitable for fabrication of light-emitting diodes because it is

a. An indirect band gap semiconductor
b. A direct band gap semiconductor
c. A wide band gap semiconductor
d. None of the above
Ans. a. An indirect band gap semiconductor

8) A Zener diode

a. Has a high forward voltage rating
b. Has a sharp breakdown at low reverse voltage
c. Is useful as an amplifier
d. None of the above
Ans. b. Has a sharp breakdown at low reverse voltage

9) Which of these is a best description of a Zener diode?

a. It operates in the reverse region
b. It is a constant voltage device
c. It is a constant current device
d. All of the above
Ans. b. It is a constant voltage device

Electrical Online Test 25

10) When two Zener diodes each of 10 V and 15 V are connected in series, then the overall voltage between them when they are in conduction is

a. 10 V
b. 25 V
c. 15 V
d. Zero
Ans. c. 15 V

11) The LED is usually made of materials like

a. GaAs
b. C and Si
c. GeAs
d. None of these
Ans. a. GaAs

12) Varactor diodes are used in FM receivers to obtain

a. Automatic frequency control
b. Automatic gain control
c. Automatic volume control
d. None of the above
Ans. a. Automatic frequency control

13) No-load voltage of power supply is 100 V and full-load voltage is 80 V, the percentage of regulation is

a. 0
b. 25
c. 15.75
d. None of above
Ans. b. 25

14) Zener diodes are used as

a. Reference voltage elements
b. Reference current elements
c. Reference resistance
d. None of these
Ans. a. Reference voltage elements

Electrical Online Test 25

15) Zener diodes are

a. Specially doped p-n junctions
b. Normally doped p-n junctions
c. Lightly doped p-n junctions
d. None of the above
Ans. a. Specially doped p-n junctions

16) A general propose diode is more likely to suffer an avalanche breakdown rather than a Zener breakdown because

a. It is lightly doped
b. It is heavily doped
c. It has weak covalent bonds
d. None of the above
Ans. a. It is lightly doped

17) Zener diode

a. Has a high forward voltage rating
b. Is useful as an amplifier
c. Has a sharp breakdown at low reverse voltage
d. None of the above
Ans. c. Has a sharp breakdown at low reverse voltage

18) If the junction temperature of LED is increased the radiant output power

a. Decreases
b. Increases
c. Remains the same
d. None of the above
Ans. a. Decreases

19) The Zener effect is valid approximately

a. Below 5 V
b. Above 5 V
c. Equal to 5 V
d. None of the above
Ans. a. Below 5 V

20) The clipping action of a diode requires that its forward resistance

a. Be zero
b. Have a finite value
c. Be infinite
d. None of the above
Ans. a. Be zero

Electrical Online Test 25

21) For a low voltage rectification

a. Two diode full-wave rectifier is suitable
b. Both bridge and full-wave rectifier are suitable
c. Bridge rectifier is suitable
d. None of the above
Ans. a. Two diode full-wave rectifier is suitable

22) If Vm is the peak value of an applied voltage in a half-wave rectifier with a large capacitor across the load, then PIV is

a. Vm
b. Vm/2
c. 2Vm
d. None of these
Ans. c. 2Vm

23) The most significant component of ripple voltage in a half-wave rectifier is contained in

a. Fundamental frequency
b. Second harmonic
c. DC component
d. None of the above
Ans. a. Fundamental frequency

Electrical Online Test 25

24) The disadvantages of capacitor input LC filter are

a. High cost, more weight and external field produced by a series inductor
b. High cost, less weight
c. Low cost, more weight
d. None of these
Ans. a. High cost, more weight and external field produced by a series inductor

25) Larger the value of the capacitor filter

a. Smaller the dc voltage across the load
b. Longer the time that current pulse flows through the diode
c. Larger the peak current in the rectifying diode
d. None
Ans. c. Larger the peak current in the rectifying diode

Electrical Online Test 25