Question

A loss free transformer has 500 turns on its primary winding and 2500 in secondary. The meters of the secondary indicate 200 volts at 8 amperes under these conditions. The voltage and current in the primary is

• A. 100 V, 16 A
• B. 40 V, 40 A
• C. 160 V, 10 A
• D. 80 V, 20 A

Answer 1

Answer: (B)

40 V, 40 A

Answer 2

$\frac{V_{p}}{V_{s}} = \frac{N_{p}}{N_{s}} = \frac{500}{2500} = \frac{1}{5} \Rightarrow V_{p} = \frac{200}{5} = 40\mspace{6mu} V$

Also $i_{p}V_{p} = i_{s}V_{s} \Rightarrow i_{p} = i_{s}\frac{V_{s}}{V_{p}} = 8 \times 5 = 40\mspace{6mu} A$