Question

At what points of the electric dipole experience a zero torque and non zero force in a non uniform electric field?

Answer 1

For the torque

we know that

torque = EPsinø

so if ø will we 0 degree then
torque will be
torque = EPsin0
torque = EP.0
torque = 0 Nm

for the force
since it a dipole so the magnitude of each charge will be same so to equal the force their distance from each charge will be same so the point where the net force will be zero is at the midpoint of the dipole.

let the distance of the dipole will be 2*l so the distance of midpoint will be l
so each force will be

f(+ve) = 1/4πE * q*q/l^2
f(-ve) = 1/4πE * q*q/l^2
since the direction of each force is opposite to each other so they cancel each other so we get net force equals to zero.