Question

how to derive t= p x E, torque for an electric dipole.

Answer 1

can you point of direction of p ?

Answer 2

Recall what happens in an electric field.

The negative charge will move towards the source of electric field, while the positive charge will move away.


Torque is r x F.
Over here you can see that total torque is r x 2qE
2r=d
so torque is then qd x E
or the usual p x E

If you understood what I typed you shouldtry to solve shubhamsg's question.