If a circuit has 12 V across a 4 Ω resistor, what is the power dissipated?

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Prepare for the NCCER Introduction to Electrical Circuits exam. Utilize flashcards and multiple choice questions with hints and explanations to excel on your test.

Multiple Choice

If a circuit has 12 V across a 4 Ω resistor, what is the power dissipated?

Explanation:
Power dissipated in a resistor is determined by P = V^2 / R. With 12 V across a 4 Ω resistor, P = 12^2 / 4 = 144 / 4 = 36 W. You can confirm by finding the current first: I = V / R = 12 / 4 = 3 A, then P = VI = 12 × 3 = 36 W, or P = I^2 R = 3^2 × 4 = 36 W. So the resistor dissipates 36 watts.

Power dissipated in a resistor is determined by P = V^2 / R. With 12 V across a 4 Ω resistor, P = 12^2 / 4 = 144 / 4 = 36 W. You can confirm by finding the current first: I = V / R = 12 / 4 = 3 A, then P = VI = 12 × 3 = 36 W, or P = I^2 R = 3^2 × 4 = 36 W. So the resistor dissipates 36 watts.

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