Question

The coils of a step down transformer have 500 and 5000 turns. In the primary coil an ac of 4 ampere at 2200 volts is sent. The value of the current and potential difference in the secondary coil will be

• A. 20 A, 220 V
• B. 0.4 A, 22000 V
• C. 40 A, 220 V
• D. 40 A, 22000 V

Answer 1

Answer: (C)

40 A, 220 V

Answer 2

$\frac{N_{p}}{N_{s}} = \frac{V_{p}}{V_{s}} = \frac{i_{s}}{i_{p}}$. The transformer is step-down type, so primary coil will have more turns. Hence

$\frac{5000}{500} = \frac{2200}{V_{s}} = \frac{i_{s}}{4} \Rightarrow V_{s} = 220\mspace{6mu} V,\mspace{6mu} i_{s} = 40\mspace{6mu} amp$