Question

p-n-p transistor is used in common-emitter mode in an amplifier circuit. A change of  in the base-current brings a change of 2 mA in collector-current and of 0.04 V in base-emitter voltage. Find the input resistance  and the base-current amplification factor . If a load resistance of  is used, then find the voltage-gain of the amplifier. 

Solution

Correct option is

 

For a transistor in common-emitter mode, the input resistance is given by 

         

              

              

              

The base-current amplification factor is given by   

        

           

           

           = 50. 

If  be the output (load) resistance, then the voltage-gain is given by 

        

              

              

              = 300.

SIMILAR QUESTIONS

Q1

The current-gain of a transistor in a common-base arrangement is 0.98. Find the change in collector-current corresponding to a change of 5.0 mA in emitter-current. What would be the change in the base-current?

Q2

In a common-base amplifier the load-resistance of the output circuit is  and the resistance of the input circuit is . If current-gain be 0.95, calculate the voltage-gain and the power gain.

Q3

In input and output resistances in a common-base amplifier circuit are  respectively. If the current-gain  is 0.98, then find the voltage gain. If the emitter-current is 2 mA, then find the collector-current and the base-current. 

Q4

The a-c current gain  of a transistor is 150. What will be the change in the collector-current for a change of  in its base-current? What will be the change in the emitter-current? 

Q5

Find the voltage gain and power gain in a transistor amplifier in common-emitter configuration when  and the input and the output ersistance are .

Q6

The input resistance of a silicon transistor is . Its base-current is changed by  which results in a change of 2 mA in the collector-current. The transistor is used as a common-emitter amplifier with a load resistance of . What is the voltage gain of the amplifier? Also calculate the transconductance of the transistor.

Q7

A change of 0.2 mA in base-current causes a change of 5 mA in the collector-current for a common-emitter amplifier. Find the a-c current gain of the transistor.   

Q8

In an n-p-n transistor, 1010 electrons enter the emitter in 10–6 s. 2% of the electrons are lost in the base. Calculate the current transfer ratio and the current amplification factor. Charge on electron is .

Q9

A transistor is connected in common-emitter configuration. The collector-supply is 8 V and the voltage drop across a resistor of  in the collector circuit is 0.5 V. If the current-gain factor  is 0.96, find the base-current.  

Q10

A transistor has three impurity regions. All the three regions have different doping levels. In order of increasing doping level, the regions are :