Q. In a step-up transformer the turn ratio is 1 : 10. A resistance of $200\ ohm$ connected across the secondary is drawing a current of $0.5\ A$. What is the primary voltage and current
A) $50\ V,\ 1\ amp$
B) $10\ V,\ 5\ amp$
C) $25\ V,\ 4\ amp$
D) $20\ V,\ 2\ amp$
Explanation
(b) $N_{p}:N_{s} = 1:10$ and $V_{s} = 0.5 \times 200 = 100\ V$
$\frac{V_{s}}{V_{p}} = \frac{N_{s}}{N_{p}} \Rightarrow \frac{100}{V_{p}} = \frac{10}{1} \Rightarrow V_{p} = 10\ V$
$\frac{i_{p}}{i_{s}} = \frac{N_{s}}{N_{p}} \Rightarrow \frac{i_{p}}{0.5} = \frac{10}{1},\ i_{p} = 5\ amp$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.