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JAMB Physics 1997 Question 46

Question 46

Alternating Current Circuits

The power dissipated in an a.c. circuit with an r.m.s. current of 5 A, r.m.s. voltage of 10 V and a phase angle of 60° is

  1. A.25 W
  2. B.50 W
  3. C.120 W
  4. D.125 W
Show the answer and explanation

Answer: A (25 W)

Explanation

Average a.c. power P = IV cos φ = 5 × 10 × cos 60° = 25 W.