Transistor Audio Power Amplifiers Mcqs - Set 1

1)   The output transformer used in a power amplifier is a _____________ transformer?

a. 1:1 ratio
b. Step-up
c. Step-down
d. None of the above
Answer  Explanation 

ANSWER: Step-down

Explanation:
No explanation is available for this question!


2)   The pulsating d.c. applied to power amplifier causes________________?

a. Burning of transistor
b. Hum in the circuit
c. Excessive forward voltage
d. None of the above
Answer  Explanation 

ANSWER: Hum in the circuit

Explanation:
No explanation is available for this question!


3)   If the gain versus frequency curve of a transistor amplifier is not flat, then there is distortion ?

a. Amplitude
b. Intermodulation
c. Frequency
d. None of the above
Answer  Explanation 

ANSWER: Frequency

Explanation:
No explanation is available for this question!


4)   If the power rating of a transistor is 1W and collector current is 100mA, then maximum allowable collector voltage is________________?

a. 1V
b. 100V
c. 20V
d. 10V
Answer  Explanation 

ANSWER: 10V

Explanation:
No explanation is available for this question!


5)   What will be the collector efficiency of a power amplifier having zero signal power dissipation of 5 watts and a.c. power output of 2 watts ?

a. 20%
b. 80%
c. 40%
d. 50%
Answer  Explanation 

ANSWER: 40%

Explanation:
No explanation is available for this question!


6)   The driver stage usually employs_________________?

a. Class A power amplifier
b. Push-pull amplifier
c. Class C amplifier
d. None of the above
Answer  Explanation 

ANSWER: Class A power amplifier

Explanation:
No explanation is available for this question!


7)   The output signal voltage and current of a power amplifier are 5V and 200 mA; the values being r.m.s. What is the power output ?

a. 1 W
b. 2 W
c. 4 W
d. None of the above
Answer  Explanation 

ANSWER: 1 W

Explanation:
No explanation is available for this question!


8)   The push-pull circuit must use ______________ operation?

a. Class A
b. Class C
c. Class B
d. Class AB
Answer  Explanation 

ANSWER: Class B

Explanation:
No explanation is available for this question!


9)   What turn ratio (Np/Ns) of transformer is required to match 4 O speaker to a transistor having an output impedance of 8000 O ?

a. 2
b. 7
c. 3
d. None of the above
Answer  Explanation 

ANSWER: 7

Explanation:
No explanation is available for this question!


10)   For the same a.c. power output as above, what should be the minimum power rating of transistor for class B operation?

a. 10 W
b. 4 W
c. 8 W
d. None of the above
Answer  Explanation 

ANSWER: 4 W

Explanation:
No explanation is available for this question!