NECO 2004 Physics · Question 33

Calculate the energy stored in an inductor of inductance 0.5H when a current of 3A flows through it.

Options

A.15.00 J
B.9.45 J
C.6.00 J
D.4.50J
E.2.25 J

Answer: E. 2.25 J

Explanation written with AI and checked against the answer key

Analyze the question: We need the energy stored in the magnetic field of an inductor, given L = 0.5 H and I = 3 A. Concept: The energy stored in an inductor is E = ½ L I² Solution: E = ½ × 0.5 × (3)² E = ½ × 0.5 × 9 E = 0.25 × 9 E = 2.25 J Checking against the options: 2.25 J matches option E. Answer: E. 2.25 J Tip: Remember that the energy formula for an inductor has the same shape as kinetic energy (½mv²) and the energy in a capacitor (½CV²). Always square the current before multiplying. A common mistake is to compute ½ × 0.5 × 3 = 0.75, or to forget the ½ and get 4.5 J (option D), which is a trap answer. Whenever you see ½ L I², square first, then multiply.

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