NECO 2001 Physics · Question 27

A 220 V, 60 Hz alternating current supply is connected to an inductor of 3.5H. What is the current passing through the inductor?

Options

A.0.0167 A
B.0.1670 A
C.1.6700 A
D.16.7000 A
E.167.0000 A

Answer: B. 0.1670 A

Explanation written with AI and checked against the answer key

Analyze the question: An AC supply is connected to a pure inductor. We need the current, which depends on the inductor's opposition to AC, called inductive reactance. Concept: Inductive reactance: X_L = 2πfL Current: I = V / X_L Solution: Step 1: Find the reactance X_L = 2 × π × 60 × 3.5 X_L = 2 × 3.142 × 60 × 3.5 X_L = 1319.5 Ω (approximately) Step 2: Find the current I = V / X_L = 220 / 1319.5 I ≈ 0.1667 A So I ≈ 0.167 A. Checking the options: 0.1670 A matches option B. (Note: 220 V is taken as the rms value, so this is the rms current.) Tip: For inductor questions, always compute X_L = 2πfL first, then use I = V/X_L. A quick estimate helps you eliminate options: 2π × 60 is about 377, and 377 × 3.5 is about 1320. Dividing 220 by about 1320 gives roughly 1/6, or about 0.17, so you can immediately see the answer is in the tenths and not 0.0167 or 1.67.

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