passwella.
Menu

JAMB Physics 2008 Question 43

Question 43

Electromagnetic Induction

A step-down transformer has a power output of 50W and efficiency of 80%. If the mains supply voltage is 200V, calculate the primary current of the transformer.

  1. A.0.31A.
  2. B.3.20A.
  3. C.3.40A.
  4. D.5.00A.
Show the answer and explanation

Answer: A (0.31A.)

Explanation

Input power = output ÷ efficiency = 50 ÷ 0.8 = 62.5 W. Primary current = 62.5 ÷ 200 ≈ 0.31 A.