Q. A step-down transformer is used on a 1000 V line to deliver 20 A at 120 V at the secondary coil. If the efficiency of the transformer is 80%, the current drawn from the line is
A) 3 A
B) 30 A
C) 0.3 A
D) 2.4 A
Explanation
(a) $\ \ \ \ \ \frac{80}{100} = \frac{120 \times 20}{1000 \times I_{p}}$
$I_{p} = \frac{120 \times 20}{1000 \times 0.8} = 3\ A$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.