Question

One of the differences/similarity, in the operation of a transistor amplifier, and a step–up transformer, is 

(1) In transistor, if voltage increases, current also increases, in step–up transformer, if voltage increases, current decreases

(2) In transistor, if voltage increases, current increase; in step–up transformer, if voltage increase, current increases

(3) In both of them, if voltage increases, current also increases

(4) In both of them, if voltage increases, current decreases

Answer 1

Correct option: (1)

Explanation: 

The transistor can bring about an increases in voltage along with an increase in current. This is because the increased power, in the ‘output’ of a transistor, comes at the expense of the power supplied by the biasing battery. 

In a step–up transformer, there is no such power source. Hence the ‘output’ power – even in the case of an ideal transformer – can at best be equal to the ‘input’ power. The increase in voltage, here, is accompanied by a decrease in current, and vice–versa.