Question

Two long straight conductors carrying equal current kept parallel at a separation of $d$ metre experience a force per unit length. If the distance of separation is made $2d$, then to maintain the same force per unit length on each conductor, the current in each conductor should be increased to

• A. $2I$
• B. $\sqrt{2}I$
• C. $\dfrac{I}{\sqrt{2}}$
• D. $1.5I$
• E. $3I$

Hint:

Physics Tip: For parallel wires, force $\propto \dfrac{I^2}{r}$. If distance doubles, current must multiply by $\sqrt{2}$ to keep force same.

Answer 1

The Correct Option is B