Question

In a step - up transformer the turn ratio is 3 : 2 A Leclanche cell of e.m. f. 1.2 V is connected across the primary . The voltage across the secondary is

• A. $3V$
• B. $Zero$
• C. $0.75V$
• D. $7.5V$

Answer 1

The correct option is A $3V$

Answer : B. Zero

Explanation :

A Leclanche cell produces D.C voltage. The Leclanche cell in the question provides 1.2 V across the primary winding (or coil) of the step up transformer. But, this is D.C voltage. A D.C voltage (which does not change with time like A.C) across the primary winding can not change the magnetic flux linked with the secondary winding. So, the Leclanche cell can not induce an e.m.f in the secondary winding. Therefore, voltage across the secondary winding will be zero.

Remember that only A.C voltage in the primary coil can induce an e.m.f in the secondary coil and thus produce a voltage across the secondary coil.