NEET Physics: Torque on a dipole in a uniform electric field Practice Questions
13 free multiple-choice questions on Torque on a dipole in a uniform electric field (Electrostatics) for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. An electric dipole of moment p is placed in a uniform electric field E. The torque experienced by the dipole is maximum when the angle between the dipole moment vector p⃗ and the electric field vector E⃗ is:
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Correct answer: C — 90°
The torque τ on an electric dipole in a uniform electric field is given by τ= pE sin θ, where θ is the angle between p⃗ and E⃗. The torque is maximum when sin θ is maximum, which occurs when θ= 90°.
Q2. The potential energy of an electric dipole placed in a uniform electric field is U = -pE cos θ. If the dipole is oriented such that cos θ= 0, what is the corresponding potential energy of the dipole?
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Correct answer: C — 0
The potential energy is given by U = -pE cos θ. If cos θ= 0, then U = -pE(0) = 0. This occurs when θ= 90°, which corresponds to the configuration where the potential energy is zero.
Q3. What is the direction of the torque experienced by an electric dipole placed in a uniform electric field?
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Correct answer: D — Perpendicular to both the dipole moment and the electric field
The torque (τ⃗ = p⃗ × E⃗) is always perpendicular to both the dipole moment vector (p⃗) and the electric field vector (E⃗).
Q4. A dipole is oriented at an angle θ= 60° with respect to a uniform electric field. If the magnitude of the electric field is E and the magnitude of the magnetic moment is p, what is the magnitude of the torque acting on the dipole?
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Correct answer: D — pE √3/2
The torque is given by τ= pE sin θ. Substituting the given values, τ= pE sin(60°) = pE (√3/2).
Q5. The torque acting on an electric dipole placed in a uniform electric field is maximum when the dipole moment is oriented at which angle with respect to the direction of the electric field?
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Correct answer: B — 90°
The magnitude of the torque is τ= pE sin θ. The maximum value occurs when sin θ is maximum, which happens when θ= 90°. Therefore, the torque is maximum when the dipole moment is perpendicular to the electric field.
Q6. If the magnetic moment of a dipole is p and it is placed in a uniform electric field E, the expression for the torque magnitude is:
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Correct answer: D — pE sin θ
The magnitude of the torque τ on a dipole in a uniform field is τ= pE sin θ, where θ is the angle between p⃗ and E⃗.
Q7. If the magnetic dipole moment is p and it is placed in a uniform magnetic field B, the magnitude of the torque experienced is pB sin θ. If the dipole is oriented such that θ=0°, what is the torque?
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Correct answer: B — 0
When θ= 0°, sin(0°) = 0. Therefore, the torque experienced by the magnetic dipole is zero.
Q8. For a dipole placed in a uniform electric field, the magnitude of the torque acting on it is given by:
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Correct answer: D — pE sin(90°)
The magnitude of the torque is τ= pE sin θ, where θ is the angle between the dipole moment vector and the electric field vector. When θ=90°, sin(90°)=1, so τₘₐₓ = pE.
Q9. A dipole with magnetic moment p is placed in a uniform electric field E. The torque acting on the dipole is given by τ= pE sin θ, where θ is the angle between the dipole moment vector and the electric field vector. What is the condition for the torque acting on the dipole to be zero?
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Correct answer: A — θ= 180°
The torque is given by τ= pE sin θ. For the torque to be zero (τ=0), sin θ must be zero. This occurs when θ= 0° or θ= 180°. In both these cases, the dipole moment is aligned parallel or anti-parallel to the electric field.
Q10. An electric dipole of magnetic moment p is placed in a uniform electric field E. If the dipole is oriented such that its dipole moment is parallel to the electric field, what is the torque experienced by the dipole?
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Correct answer: A — 0
The torque is given by τ= pE sin θ. If the dipole moment p⃗ is parallel to the electric field E⃗, then θ= 0°, and sin(0°) = 0. Thus, the torque is zero.
Q11. A small electric dipole is placed in a uniform electric field. The torque experienced by the dipole depends on the relative orientation of the dipole moment and the electric field. In which direction is the torque vector directed?
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Correct answer: B — Perpendicular to the electric field
The torque (τ⃗) on an electric dipole in a uniform electric field (E⃗) is given by τ⃗ = p⃗ × E⃗. Since the cross product of two vectors results in a vector perpendicular to both, the torque is always perpendicular to both the dipole moment (p⃗) and the electric field (E⃗).
Q12. If an electric dipole is placed in a uniform electric field, and its dipole moment is perpendicular to the electric field, what is the magnitude of the torque acting on the dipole?
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Correct answer: B — pE
When p⃗ ⊥ E⃗, the angle θ= 90°. The torque is τ= pE sin(90°) = pE × 1 = pE.
Q13. A dipole is placed in a uniform external electric field E⃗. If the angle between the dipole moment vector p⃗ and the electric field vector E⃗ is 0°, what is the resulting torque experienced by the dipole?
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Correct answer: A — Zero torque
The torque τ⃗ experienced by an electric dipole in a uniform electric field is given by τ⃗ = p⃗ × E⃗, and its magnitude is τ= pE sin θ, where θ is the angle between p⃗ and E⃗. If θ= 0° (or 180°), sin θ= 0, which means the torque is zero.
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