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Question:

A dipole of dipole moment 'p' is placed in non-uniform electric field along x-axis. Electric field is increasing at the rate of 1 Vm⁻¹. The force on dipole is:

0

p

2p

p/2

Solution:

Force is given as the negative gradient of potential energy.
F = -dU/dx
Potential energy for an electric dipole is
U = -p⃗.E⃗
So, we get the force as,
F = p(dE/dx) = p
As dE/dx = 1