Question

A step-up transformer has 300 turns of primary winding and 450 turns of secondary winding. A primary is connected to 150 volt and the current flowing through it is 9A. The current and voltage in the secondary are

• A. 13.5 A, 225 V
• B. 13.5 A, 100 V
• C. 4.5 A, 100 V
• D. 6.0 A, 225 V

Hint:

In a transformer, the current and voltage are inversely related, while the number of turns in the primary and secondary windings are directly related.

Answer 1

The Correct Option is D

Step 1: Use the transformer formula.
For a transformer, the voltage and current are related by the following formula: \[ \frac{V_1}{V_2} = \frac{N_1}{N_2}, \quad \frac{I_1}{I_2} = \frac{N_2}{N_1} \] where \( V_1 \) and \( V_2 \) are the voltages, \( I_1 \) and \( I_2 \) are the currents, and \( N_1 \) and \( N_2 \) are the number of turns in the primary and secondary windings, respectively.
Step 2: Apply the formula.
Given that \( N_1 = 300 \), \( N_2 = 450 \), \( V_1 = 150 \, \text{V} \), and \( I_1 = 9 \, \text{A} \), we can find \( V_2 \) and \( I_2 \): \[ V_2 = \frac{N_2}{N_1} \times V_1 = \frac{450}{300} \times 150 = 225 \, \text{V} \] \[ I_2 = \frac{N_1}{N_2} \times I_1 = \frac{300}{450} \times 9 = 6.0 \, \text{A} \]
Step 3: Conclusion.
The current and voltage in the secondary are \( 6.0 \, \text{A} \) and \( 225 \, \text{V} \), so the correct answer is (D).