An electron moves round a circular path of radius 0.1 m about an infinite linear charge of density +1 μC/m. The speed of the electron will be
Answer & explanation
Correct answer: option 3
$\text{Force applied by electric field of wire on charge }F = \frac{q\lambda}{2\pi \epsilon_0 R}$
$ \text{This force will give centripetal force }\Rightarrow \frac{mv^2}{R} = \frac{q\lambda}{2\pi \epsilon_0 R} $
$\Rightarrow v = \sqrt{\frac{q\lambda}{2\pi \epsilon_0 mR}} = 5.6\times 10^7m/s$