Q. A generator at a utility company produces 100 A of current at 4000 V. The voltage is stepped up to 240000 V by a transformer before it is sent on a high voltage transmission line. The current in transmission line is
A) 3.67 A
B) 2.67 A
C) 1.67 A
D) 2.40 A
Explanation
(c) For step-up transformer,
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ V_{s} > V_{p}\ and\ I_{s} < I_{p}$
For an ideal transformer,
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ V_{s}I_{s} = V_{p}I_{p}$
$\therefore\ \ \ \ \ \ \ \ \ \ 240000I_{s} = 100 \times 4000$
or $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ I_{s} = 1.67\ A$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.