In a common emitter amplifier, the phase difference between input signal and output signal is:

1. zero             

2. $\mathrm{\pi }$               

3. $\frac{\mathrm{\pi }}{2}$               

4. $\frac{\mathrm{\pi }}{4}$

In an NPN transistor amplifier, if 98% of electrons emitted from the emitter reach the collector, then the value of collector current for the base current of 40 $\mu$A will be:

1. 1.96 mA             

2. 1.92 mA             

3. 1.96 A             

4. 1.92 A

In a common emitter circuit, if V_CC is changed by 0.2 V, collector current changes by 4 x 10^–3 mA. The output resistance will be:

1. 10 k$\mathrm{\Omega }$ 

2. 30 k$\mathrm{\Omega }$ 

3. 50 k$\mathrm{\Omega }$ 

4. 70 k$\mathrm{\Omega }$

An NPN transistor conducts when:

In a transistor, a change of 8.0 mA in the emitter current produces a change of 7.8 mA in the collector current. What change in the base current is necessary to produce the same change in the collector current?
1. 50 $\mathrm{\mu }$A 
2. 100 $\mathrm{\mu }$A
3. 150 $\mathrm{\mu }$A 
4. 200 $\mathrm{\mu }$A

In a transistor circuit shown here, the base current is  35 $\mathrm{\mu }$A  and the potential difference across emitter-base junction is 4.5 V. The value of the resistor R_b is:
                 

1. 128.5 k$\mathrm{\Omega }$

2. 257 k$\mathrm{\Omega }$

3. 380.05 k$\mathrm{\Omega }$

4. None of these

When a transistor is used as a switch, it is in:

1.  active state.

2.  cut-off state.

3.  saturation state.

4.  both cut-off and saturation states are possible.

Use of transistor as an amplifier works in the:

1.  Cut off region

2.  Saturation region

3.  Passive region

4.  Active region

When the NPN transistor is used as an amplifier:
1. the electrons move from base to collector.
2. the holes move from emitter to base.
3. the electrons move from collector to base.
4. the holes move from collector to emitter.

The transfer ratio of a transistor is 50. The input resistance of the transistor when used in the common-emitter configuration is 1 k$\mathrm{\Omega }$. The peak value for an A.C input voltage of 0.01 V peak is:

1. 100 μA

2. 0.01 mA

3. 0.25 mA

4. 500 μA