# Digital Electronic 9

Objectives for Electrician and Wireman: Digital Electronic 9

Subject: Digital Electronic 9

Part 9: Objective questions and answers of Digital Electronics

Q1. What is the power gain of CE amplifier with a voltage gain of 66 and Beta of the transistor is 100?

a) 1.5

b) 166

c) 0.66

d) 6600

Q2. What is the effect of pinch-off voltage in JFET?

a) No depletion region exists

b) Drain current becomes zero

c) Reverse bias voltage becomes zero

d) Width of channel has maximum value

Q3. In amplifiers, transistors are used for?

a) Enlarging small signals

b) Reducing a signal

c) Converting an A.C. signal into D.C. signal

d) All the above stated purposes

Q4. The emitter bypass capacitor used in a CE type amplifier affects?

a) The input impedance

b) The gain of the circuit

c) The frequency of the amplified signal

d) Both A and B

Q5. Small signal amplifiers are also known as?

a) Large power amplifiers

b) Medium power amplifiers

c) Low power amplifiers

d) Both medium and low power amplifiers

Q6. The minimum value of input coupling capacitor for 20 Hz to 20 khz amplifier should be atleast?

a) 10 degree F

b) 1 degree F

c) 4.7 degree F

d) 10 degree F

Q7. The gain (voltage or current) of a CE amplifier is highest at?

a) High frequency

b) Low frequency

c) Mid frequency

d) All frequency

Q8. The advantage of impedance coupling (using a choke as collector load) is ?

a) Low d.c. Resistance and high impedance

b) Low d.c. Resistance and low impedance

c) High d.c. Resistance and high impedance

d) High d.c. Resistance and low impedance

Q9. In a.f. Amplifiers, the most commonly used method of coupling is ?

a) RC coupling

b) Impedance coupling

c) Transformer coupling

d) Direct coupling

Q10. The first stage of an audio amplifier is designed to work as class 'A' due to its ?

a) High efficiency

b) High power gain

c) Low distortion

d) All the above stated reasons

Q11. If a portion of output voltage is fed back to the input of an amplifier at a phase difference of 180 degree, the phenomenon is called?

a) Negative feedback

b) Positive feedback

c) Voltage feedback

d) Current feedback

Q12. If the emitter resistor is not bypassed by a capacitor, the feedback circuit is called ?

a) Current feedback

b) Voltage feedback

c) Inverting voltage feedback

d) Fold back

Q13. The automatic volume control (A.V.C.) system of a radio receiver incorporates ?

a) Positive feedback

b) Negative feedback

c) Inverting feedback

d) No feedback

Q14. A power amplifier is essentially?

a) An impedance matching device

b) A noise amplifier

c) A current amplifier

d) A voltage amplifier

Q15. The efficiency of a class 'B' amplifier is around?

a) 10%-30%

b) 30%-50%

c) 50%-60%

d) 100%

Q16. In class 'B' amplifier, the output current flows for?

a) Less than half input cycle

b) More than half input cycle

c) Half input cycle

d) Entire input cycle

Q17. Which one can be the possible reason for 'distorted output' in an A.F. amplifier?

a) Open coupling capacitor

b) Open ON/OFF switch

c) Very high input signal level

d) Open bypass capacitor

Q18. Suitable equipment for fault-finding in A.F. amplifiers is?

a) Signal generator

b) Signal tracer

c) Signal injector

d) Any one of the above stated equipment’s

Q19. An Op-Amp. Is designed to amplify?

a) A.C. Signals only

b) D.C. Signals only

c) Both A.C. And D.C. Signals

d) Pulse signals only

Q20. In an Op-Amp. The use of negative feedback increases?

a) The frequency response

b) Stability of amplification

c) Gain

d) None of the above stated

Part 9: Objective questions and answers of Digital Electronics