What is the total resistance of a two-wire circuit that spans a distance of 200' each way with a resistance of 1.21Ω per 1,000'?

• A. 0.484Ω
• B. 0.748Ω
• C. 0.621Ω
• D. 0.908Ω

Answer: (A)

To determine the total resistance of the two-wire circuit, we first need to calculate the resistance incurred along the length of the circuit. Since the circuit spans a distance of 200 feet each way, the total length of the circuit is 400 feet (200 feet out and 200 feet back).

Given that the resistance of the wire is 1.21Ω per 1,000 feet, we can find the resistance per foot:

1.21Ω / 1,000 feet = 0.00121Ω per foot.

Next, we can calculate the total resistance for 400 feet:

Total resistance = length × resistance per foot

Total resistance = 400 feet × 0.00121Ω/foot = 0.484Ω.

Thus, the total resistance for the entire circuit is 0.484Ω, which corresponds to the correct answer. This method of calculation clearly illustrates how the total resistance in a wire circuit can be determined based on the material’s resistance per unit length and the total length of the circuit.