BJT Amplifiers and Oscillators MCQs

Question 1

The PNP/NPN amplifier is used in place of ordinary direct-coupled amplifier in order to

Accepted Answer

avoid the problem of growing Vc's

Answer

achieve greater stability

Answer

amplify both dc and ac voltages

Answer

achieve greater amplification

Question 2

Regarding differential amplifier which statement is wrong?

Accepted Answer

it is not much used ICs

Answer

a single-stage amplifier has two inpute, one across each base

Answer

it has the ability to amplify the differnce between two signals

Answer

it is used to eliminate noise picked up along a short transmission line

Question 3

Cascaded amplifiers which find wide use in ICs are coupled.

Accepted Answer

direct

Answer

capacitively

Answer

transformer

Answer

inductively

Question 4

An amplifier is used to amplify a 307c Hz square wave with a sag not exceeding 1%. Maximum permissible lower 3 dB frequency of the amplifier is___hertz.

Accepted Answer

30

Answer

300

Answer

0.3

Answer

100

Question 5

The rise time of an amplifier is 200 ns. Its upper 3-dB frequency is

Accepted Answer

1.75 MHz

Answer

70 MHz

Answer

1.5 MHz

Answer

70 kHz

Question 6

An electronic oscillator is

Accepted Answer

an amplifier with feedback

Answer

just like an alternator

Answer

nothing but an amplifier

Answer

a converter of ac to dc energy

Question 7

The oscillator circuit that uses a tapped coil in the tuned circuit is

Accepted Answer

Hartley

Answer

multivibrator

Answer

Colpitts

Answer

Armstrong

Question 8

The oscillator that uses tapped capacitors in the tuned circuit is

Accepted Answer

Colpitts

Answer

astable multivibrator

Answer

(d) both (a) and (b)

Answer

none of the above

Question 9

An oscillator produces oscillations due to

Accepted Answer

positive feedback

Answer

negative feedback

Answer

partly positive and partly negative feedback

Answer

neither positive nor negative feedback