Question

A large sheet carries uniform surface charge density `sigma` . A rod of length 2l has a linear charge density `lambda` on one half and `-lambda` on the second half. The rod is hinged at the midpoint O and makes an angle `theta` with the normal to the sheet. The torque experience by the rod is

A. `(sigmalambdal^(2))/(2epsilon_(0))costheta`
B. `(sigmalambdal^(2))/(epsilon_(0))cos^(2)theta`
C. `(sigmalambdal^(2))/(2epsilon_(0))sintheta`
D. zero

Answer 1

Correct Answer - C

rArr By symmetry `tau=(sigmalambdal^(2))/(2epsilon_(0))sintheta`