Question

The force per unit length between two parallel current carrying straight conductors separated by \(2d\) is given by the formula:

• A. \( \frac{\mu_0 i_1 i_2}{4\pi d} \)
• B. \( \frac{\mu_0 i_1 i_2}{8\pi d} \)
• C. \( \frac{\mu_0 i_1 i_2}{2\pi d} \)
• D. None of these

Hint:

Always substitute actual distance \(r\) in formula.

Answer 1

The Correct Option is A

Concept: Force per unit length: \[ \frac{F}{L} = \frac{\mu_0 i_1 i_2}{2\pi r} \]

Step 1: Given separation.
\[ r = 2d \]

Step 2: Substitute.
\[ \frac{F}{L} = \frac{\mu_0 i_1 i_2}{2\pi (2d)} = \frac{\mu_0 i_1 i_2}{4\pi d} \]