Problem 3.15

A thread carrying a uniform charge $\lambda$ per unit length has the configurations shown in Fig. $3.2 a$ and $b$ . Assuming a curvature radius $R$ to be considerably less than the length of the thread, find the magnitude of the electric field strength at the point $O$ .

\text { (a) } E=\frac{\lambda \sqrt{2}}{4 \pi \varepsilon_{0} R} \text { (b) } E=0 \text { . }

Constant Electric Field in a Vacuum