Question

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.

Solution

Correct option is

 

The alternating current gain  of a common-emitter is defined by 

          

 are the changes in collector-current and base-current respectively. Thus 

       

           

           = 133.3 

Now, the a-c voltage gain of a common-emitter amplifier is given by 

       

     

             = 1000. 

Now, the transconductance of the transistor is defined as 

       

 is change in base-to-emitter voltage. Further, the input resistance is given by 

       

From the last two equations, we have 

       

     

              

              .

SIMILAR QUESTIONS

Q1

The drift current in a p-n junction is :

Q2

The diffusion current in a p-n junction is 

Q3

In a p-n-p transistor with normal bias:

Q4

The base-current of a transistor is  and the collector-current is 2.05 mA. A change of  in the base-current produces a change of 0.65 mA in the collector current. Find .  

Q5

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?

Q6

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.

Q7

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. 

Q8

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? 

Q9

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

Q10

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.