NEET 2025 — Physics solution

NEET2025Physics

An electric dipole with dipole moment $5 \times 1 0^{- 6}$ C m is aligned with the direction of a uniform electric field of magnitude $4 \times 1 0^{5}$ N/C. The dipole is then rotated through an angle of $6 0^{\circ}$ with respect to the electric field. The change in the potential energy of the dipole is:

A
0.8 J
B
1.0 J
C
1.2 J
D
1.5 J

Solution

Potential energy of a dipole: $U = - pE cos θ$ . Change: $Δ U = pE (cos θ_{i} - cos θ_{f})$ .

With $θ_{i} = 0^{\circ}$ and $θ_{f} = 6 0^{\circ}$ :

$Δ U = (5 \times 1 0^{- 6}) (4 \times 1 0^{5}) (1 - \frac{1}{2}) = 2 \times \frac{1}{2} = 1$ J.

← Back to full paper

Practice more Physics

Concept-wise practice with instant solutions on Fundamenthol.

Start practicing →