Round to the nearest tenth unless indicated otherwise.
-At a fixed temperature, the resistance R of a wire varies directly as the length l and inversely as the square of its diameter d. If the resistance is 0.46 ohm when the diameter is 1 mm and the length is 230 cm, what is the
Resistance when the diameter is 2 mm and the length is 2170 cm?
A) 1.1 ohm
B) 542.5 ohm
C) 249.6 ohm
D) 2.2 ohm

Question

Quizplus · Accepted Answer

The resistance is directly proportional to the length and inversely proportional to the square of the diameter. So, R = k * l / d^2, where k is a constant. We can find k by plugging in the given values: 0.46 = k * 230 / 1^2, so k = 0.002. Now we can use this to find the resistance when the diameter is 2 mm and the length is 2170 cm: R = 0.002 * 2170 / 2^2 = 1.1 ohms.

Round to the Nearest Tenth Unless Indicated Otherwise