Question

A circular coil of $200$ turns and radius $10cm$ is placed in an uniform magnetic field of $0.1T$ normal to the plane of the coil. The coil carries a current of $5A$. The coil is made up of copper wire of cross-sectional area ${10}^{-5}{m}^2$ and the number of free electrons per unit volume of copper is ${10}^{29}$. The average force experienced by an electron in the coil due to magnetic field is

• A. $5\times {10}^{-25}N$
• B. Zero
• C. $8\times {10}^{-24}N$
• D. None of these

Answer 1

The correct option is A $5\times {10}^{-25}N$

$V_d=\frac{i}{nqA}$,

Force=$F=q(V_d\times B)$,

$F=\frac{iB}{nA}=\frac{5\times 0.1}{{10}^{29}\times {10}^{-5}}=5\times {10}^{-25}N$