Start free

Physics · Electrostatics

NEET (UG) 2025 — Question 33

An electric dipole with dipole moment 5×10−6Cm5 \times 10^{-6} \mathrm{Cm} is aligned with the direction of a uniform electric field of magnitude 4×105 N/C4 \times 10^{5} \mathrm{~N} / \mathrm{C} The dipole is then rotated through an angle of 60∘60^{\circ} with respect to the electric field. The change in the potential energy of the dipole is :

  1. Option A:

    0.8 J

  2. Option B:

    1.0 J

    Correct
  3. Option C:

    1.2 J

  4. Option D:

    1.5 J

Answer: B

Step-by-step solution

Given,

p=5×10−6Cm\mathrm{p}=5 \times 10^{-6} \mathrm{Cm}

E=4×105 N/C\mathrm{E}=4 \times 10^{5} \mathrm{~N} / \mathrm{C}

θi=0∘,θf=60∘\theta_{\mathrm{i}}=0^{\circ}, \theta_{\mathrm{f}}=60^{\circ}

ΔU=Uf−Ui\Delta \mathrm{U}=\mathrm{U}_{\mathrm{f}}-\mathrm{U}_{\mathrm{i}}

=−pEcos⁡θf−(−pEcos⁡θj)=-p E \cos \theta_{f}-\left(-p E \cos \theta_{j}\right)

⇒pE(cos⁡θi−cos⁡θf)\Rightarrow \mathrm{pE}\left(\cos \theta_{\mathrm{i}}-\cos \theta_{\mathrm{f}}\right)

⇒5×10−6×4×105(1−12)=1 J\Rightarrow 5 \times 10^{-6} \times 4 \times 10^{5}\left(1-\frac{1}{2}\right)=1 \mathrm{~J}

Answer key and solution verified before publishing.

Practise Electrostatics

Start with this question, then two more from the same chapter — with a tutor that explains every step. Free.

Solve a similar one free
Exam
NEET (UG) 2025
Paper
2025 paper
Subject
Physics
Chapter
Electrostatics
Topic
Electric Dipole

More Electrostatics questions from this paper

An electric dipole with dipole moment 5 × 10 -6 Cm is aligned with… | NEET (UG) 2025 PYQ with Solution · DhiX AI