TS Mocktest 2021-8

1. Which of the following is not the advantage of HVDC transmission

A. No skin effect
B. Less corona loss
C. Less radio interference
D. HVDC transmission is economical for short distances

Answer : Less radio interference
Explanation:-

2. A single phase transmission line with an impedance of (4+j10)ohm operating with a receiving end voltage of 33kV supplying a load current of 132 A at unity power factor has a % voltage regulation of

A. 12%
B. 1.2%
C. 16%
D. 1.6%

Answer : 1.6%
Explanation:-
Voltage regulation is defined as the ratio of (Vs-Vr) and (Vr).
Vr%=(Vs-vr)/Vr*100
Vr%=(I(Rcos∅r+Xsin∅r)/Vr)*100 , Given Power factor is Unity so Cos∅=1, sin∅=0
Vr%=((132*4)/33000)*100
Vr%=1.6%

3. The output of the gate is 1 if and only if all the inputs are zero, then the gate is

A. NOR
B. AND
C. OR
D. EX- OR

Answer : NOR
Explanation:-

4. For the use of a transistor as an amplifier

A. both the junctions are forward biased
B. both the junctions are reverse biased
C. the emitter base circuit is forward biased and the collector base circuit is reverse biased
D. no matter how the transistor is biased, it always acts as an amplifier

Answer : the emitter base circuit is forward biased and the collector base circuit is reverse biased
Explanation:-

5. If the input frequency is 50 HZ then the output frequency of the full wave rectifier is

A. 50 HZ
B. 100 HZ
C. 25 HZ
D. 200 HZ

Answer : 100 HZ
Explanation:- The output frequency of full wave rectifier is 2*fin
Fo=2*50=100 Hz
The output frequency of half wave rectifier is fin
The output frequency of bridge type full wave rectifier is 2*fin

6. Which of the following devices is designed to operate with reverse bias

A. OLED, Zener diode
B. Photodiode, LED
C. Photodiode, Zener diode
D. LED, Zener diode and photodiode

Answer : Photodiode, Zener diode
Explanation:-

7. The vertical gain control of a CRO is set at a deflection sensitivity of 5V/cm. An unknown AC Sinusoidal voltage signal is applied to the Y input. A 10 cm long straight line trace is observed on the screen. Then the RMS value of the unknown voltage applied is

A. 50 V
B. 50/√2 v
C. 25 V
D. 25/√2 V

Answer : 25/√2 V
Explanation:- The unknown voltage is Deflection sesitivity*length of the trace
Unknown voltage is(Vp-p)=5*10=50 V
Then the RMS Value of Unknown voltage is Vp/√2=((Vpeak-peak)/2)/√2
=(50/2)/√2==25/√2 V

8. The minimum forward current above which the SCR starts conducting is called

A. Latching current
B. Holding current
C. leakage current
D. Saturation current

Answer : Latching current
Explanation:-

9. SCR can be protected against di/dt using

A. Series inductor
B. Series capacitor
C. Series resistor
D. snubber circuit

Answer : Series inductor
Explanation:-

10. A static device which converts fixed DC input voltage to a variable DC output voltage is called

A. Rectifier
B. Cycloconverter
C. Inverter
D. Chopper

Answer : Chopper
Explanation:-