Q. 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) $80\ V,\ 20\ A$
Explanation
(b) $\frac{V_{p}}{V_{s}} = \frac{N_{p}}{N_{s}} = \frac{500}{2500} = \frac{1}{5} \Rightarrow V_{p} = \frac{200}{5} = 40\ V$
Also $i_{p}V_{p} = i_{s}V_{s} \Rightarrow i_{p} = i_{s}\ \frac{V_{s}}{V_{p}} = 8 \times 5 = 40\ A$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.