1. A zener diode is invariably used with ?

forward bias

reverse bias

either forward bias or reverse bias

zero bias

Answer: reverse bias

Explanation:

A zener diode is invariably used with reverse bias.


2. In a full wave rectifier diode conduct for ?

one half cycle

full cycle

alternate half cycle

None of these

Answer: alternate half cycle

Explanation:

In a full wave rectifier diode conduct for alternate half cycle.


3. Iceo is related to Icbo by ?

Iceo = (B+ 1) Icbo

Iceo = Icbo

Iceo = Alpha.Icbo

None of these

Answer: Iceo = (B+ 1) Icbo

Explanation:

Iceo is related to Icbo by Iceo = (B+ 1) Icbo


4. If the temperature increases, the value of VBE ?

remains the same

is increased

is decreased

None of these

Answer: is decreased

Explanation:

If the temperature increases, the value of VBE is decreased.


5. In case of the CE amplifier the output voltage waveform is ?

in phase with input voltage waveform

always lag by 90 with respect to input voltage waveform

always lagging by 180 with respect to input voltage waveform

always lagging by 90 with respect to input voltage waveform

Answer: always lagging by 180 with respect to input voltage waveform

Explanation:

In case of the CE amplifier the output voltage waveform is always lagging by 180 with respect to input voltage waveform.


6. In a synchronous motor the maximum power developed occurs at a coupling angle of .......... degree ?

180

90

60

30

Answer: 90

Explanation:

In a synchronous motor the maximum power developed occurs at a coupling angle of 90 degree.


7. Which of the following motors will be used in electric clocks ?

D.C. series motor

D.C. shunt motor

A.C. synchronous motor

A.C. induction motor

Answer: A.C. synchronous motor

Explanation:

A.C. synchronous motors will be used in electric clocks.


8. The power developed by a synchronous motor will be maximum when the load angle is ..... ?

45

90

120

0

Answer: 90

Explanation:

The power developed by a synchronous motor will be maximum when the load angle is 90 degree.


9. In a synchronous motor, damper windings are placed on ?

rotor shaft

stator frame

pole faces

None of these

Answer: pole faces

Explanation:

In a synchronous motor, damper windings are placed on pole faces


10. In a three-phase synchronous motor, if one of the winding is short-circuited then the motor will ?

run at 1/4 of synchronous speed

not start

run with excessive vibrations

rotate at less than the rated load

Answer: not start

Explanation:

In a three-phase synchronous motor, if one of the winding is short-circuited then the motor will not start.