Question

The ratio of no. of coils in the secondary to primary step up transformer is $4:1$. If a current of $4$$A$ is applied to the primary, the current in secondary will be:

• A. $8$$A$
• B. $2$$A$
• C. $1$$A$
• D. $0.5$$A$

Answer 1

Answer: (C)

$1$$A$

In a step up transformer, the output voltage from the secondary transformer is increased in the ratio of number of coils in the primary and secondary.

Thus $\frac{V_{secondary}}{V_{primary}}=\frac{4}{1}$

Since the power $VI$ should remain the same,

$V_{primary}{I}_{primary}=V_{secondary}{I}_{secondary}$

$⟹\frac{I_{secondary}}{I_{primary}}=\frac{V_{primary}}{V_{secondary}}$

$=\frac{1}{4}$

$⟹I_{secondary}=1A$