Two electric lamps, 40 W and 80 W, are rated for the same voltage. Compare the filament resistance of both lamps.

univerkov | August 2, 2021 | education

Data: P1 (power of the first indicated lamp) = 40 W; P2 (power of the second lamp) = 80 W; U (voltage) = U1 = U2.

Comparison of resistances (using the formula P = U2 / R): U2 = P1 * R1 = P2 * R2, whence R1 / R2 = P2 / P1 = 80/40 = 2 p.

Answer: The first lamp indicated has a filament resistance 2 times more.

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