Question

A dipole is placed in x-y plane such that charges q and −q are located at x = a and x = b respectively. There exists an electric field `vec E = 2 hat i N/C` in the region. Calculate the force `vec F` and torque `vec tau` experienced by the dipole.

Answer 1

Dipole axis along x-axis `(vec p) = 2 a q hat i`

In a uniform field:

`vec F` = 0

Torque `vec tau = vec p xx vec E`

Since both `vec p` and `vec E` are along `hat i`:

`vec tau` = 0