Torque on a dipole in a uniform field
"Torque on a dipole in a uniform field" is a free, interactive Class 12 Physics simulation for NEET and JEE, built on the lesson "Dipole in a uniform external field" in Electric Charges and Fields. The field E points right. Turn the dipole and change E. Watch the two purple forces and the torque. In a uniform field a dipole feels no net force, only a torque τ = p × E, of size pE sin θ, which turns p towards E. It is largest at 90° and zero at 0° and 180°. JEE Main asked 39 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Dipole in a uniform external field in Electric Charges and Fields. Change the values and watch what happens.
In JEE Main
42 shifts analysed
39 questions from Electric Charges and Fields across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT §1.11
- In a uniform field the forces qE and −qE on the two charges are equal and opposite, so the net force on a dipole is zero.
- The two forces act at different points and form a couple: torque τ = p × E, of magnitude τ = pE sin θ, where θ is the angle between p and E.
- The torque turns the dipole towards alignment with E. It is maximum (pE) at θ = 90° and zero when p is parallel or antiparallel to E.
- In a non-uniform field there is also a net force. With p parallel to E the dipole is pulled towards the stronger field; with p antiparallel it is pushed towards the weaker field.
- A comb run through dry hair attracts uncharged bits of paper: the comb's field polarises the paper, inducing a dipole along the field, and because the comb's field is non-uniform the paper is pulled towards the comb.
Questions
3 answers
- What does the "Torque on a dipole in a uniform field" simulation show?
- The field E points right. Turn the dipole and change E. Watch the two purple forces and the torque.
- Does JEE Main ask questions from Electric Charges and Fields?
- Yes. JEE Main asked 39 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Dipole in a uniform external field" in Electric Charges and Fields (Class 12 Physics).
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