Q. Two parallel wires of length $9\ m$ each are separated by a distance $0.15\ m$. If they carry equal currents in the same direction and exert a total force of $30 \times 10^{- 7}N$ on each other, then the value of current must be
A) 2.5 $amp$
B) 3.5 $amp$
C) 1.5 $amp$
D) 0.5 $amp$
Explanation
(d) $F = 10^{- 7} \times \frac{2i^{2}}{a} \times l \Rightarrow 30 \times 10^{- 7} = 10^{- 8} \times \frac{2i^{2}}{0.15} \times 9$
$\Rightarrow i = 0.5\ A$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.