Question

A step-up transformer operates on a 230 V line and supplies a load of 2 A. The ratio of primary to secondary windings is 1:25. The current in the primary is:

• A. 50 A
• B. 25 A
• C. 12.5 A
• D. 0.08 A

Hint:

In a step-up transformer, voltage increases but current decreases in the secondary.

Answer 1

The Correct Option is A

Step 1: Concept
For an ideal transformer, the ratio of currents is inversely proportional to the turns ratio: $\frac{I_{p}}{I_{s}} = \frac{N_{s}}{N_{p}}$.
Step 2: Analysis
Given $N_{p}/N_{s} = 1/25$ and $I_{s} = 2 A$.
$I_{p} = I_{s} \times \frac{N_{s}}{N_{p}} = 2 \times 25$.
Step 3: Conclusion
The primary current $I_{p} = 50 A$.
Final Answer: (A)