A 14-ohm resistor is to be installed in a series circuit carrying .05 ampere. How much power will the resistor be required to dissipate?

A 14-ohm resistor is to be installed in a series circuit carrying .05 ampere. How much power will the resistor be required to dissipate?

• A. 0.035 W
• B. 0.7 W
• C. 0.5 W
• D. 0.0035 W

Answer: (A)

Power dissipated by a resistor is P = I^2 R. With a current of 0.05 A through a 14 Ω resistor, P = (0.05)^2 × 14 = 0.0025 × 14 = 0.035 W. You can check this by finding the voltage across the resistor: V = I R = 0.05 × 14 = 0.7 V, and then P = V I = 0.7 × 0.05 = 0.035 W (also equals V^2 / R = 0.49 / 14 ≈ 0.035 W). So the resistor dissipates 0.035 watts.

Power dissipated by a resistor is P = I^2 R. With a current of 0.05 A through a 14 Ω resistor, P = (0.05)^2 × 14 = 0.0025 × 14 = 0.035 W. You can check this by finding the voltage across the resistor: V = I R = 0.05 × 14 = 0.7 V, and then P = V I = 0.7 × 0.05 = 0.035 W (also equals V^2 / R = 0.49 / 14 ≈ 0.035 W). So the resistor dissipates 0.035 watts.