A 10 Ω resistor carries 2 A. What is the power dissipated?

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Prepare for the Electrical Academy Level 1 Test. Study with multiple choice questions, flashcards, and detailed explanations. Assess your knowledge and ace the exam!

Multiple Choice

A 10 Ω resistor carries 2 A. What is the power dissipated?

Explanation:
Power dissipated by a resistor comes from P = V I, or equivalently P = I^2 R. With a current of 2 A through a 10 Ω resistor, the voltage across it is V = I R = 2 × 10 = 20 V. Then P = V I = 20 × 2 = 40 W, which also equals I^2 R = (2)^2 × 10 = 40 W. The other numbers don’t fit these values: 20 W would require a different resistance or current (for example, R = P/I^2 = 20/4 = 5 Ω for the same current), and 200 W would require R = 200/4 = 50 Ω with the same current.

Power dissipated by a resistor comes from P = V I, or equivalently P = I^2 R. With a current of 2 A through a 10 Ω resistor, the voltage across it is V = I R = 2 × 10 = 20 V. Then P = V I = 20 × 2 = 40 W, which also equals I^2 R = (2)^2 × 10 = 40 W. The other numbers don’t fit these values: 20 W would require a different resistance or current (for example, R = P/I^2 = 20/4 = 5 Ω for the same current), and 200 W would require R = 200/4 = 50 Ω with the same current.

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