physics : class12 Torque on a dipole : Torque on an Electric Dipole : Electrostatics MCQ Questions and Answers
Practice important
Torque on a dipole
MCQ questions and answers.
Page 1
of
1
|
10
MCQ Questions
1. An electric dipole of dipole moment p is placed in a uniform electric field E at an angle θ. What is the magnitude of the torque acting on it?
A.
pE cos θ
B.
pE sin θ
C.
pE tan θ
D.
pE
Correct Answer:
pE sin θ
Explanation:
The torque on an electric dipole in a uniform electric field is given by τ = pE sin θ, where θ is the angle between the dipole moment and the electric field.
2. When an electric dipole is placed parallel to a uniform electric field, the torque acting on it is:
A.
Maximum
B.
Zero
C.
pE
D.
p/E
Correct Answer:
Zero
Explanation:
For a parallel dipole, θ = 0°. Since τ = pE sin θ and sin 0° = 0, the torque is zero.
3. The torque on an electric dipole in a uniform electric field is maximum when the angle between the dipole moment and the field is:
A.
0°
B.
30°
C.
90°
D.
180°
Correct Answer:
90°
Explanation:
Torque is τ = pE sin θ. It is maximum when sin θ = 1, which occurs at θ = 90°.
4. An electric dipole has dipole moment 2 C m and is placed in a uniform electric field of 3 N/C at 90°. What is the torque on the dipole?
A.
1.5 N m
B.
5 N m
C.
6 N m
D.
9 N m
Correct Answer:
6 N m
Explanation:
Using τ = pE sin θ, τ = 2 × 3 × sin 90° = 6 N m.
5. The direction of torque on an electric dipole in a uniform electric field is given by:
A.
p × E
B.
E × p
C.
p + E
D.
p · E
Correct Answer:
p × E
Explanation:
The torque vector on an electric dipole is given by τ = p × E, so its direction is determined by the cross product of dipole moment and electric field.
6. If the angle between an electric dipole and a uniform electric field is 30°, its torque is:
A.
pE
B.
pE cos 30°
C.
pE sin 30°
D.
Zero
Correct Answer:
pE sin 30°
Explanation:
The torque on a dipole is τ = pE sin θ. For θ = 30°, the torque is pE sin 30°.
7. An electric dipole experiences zero torque in a uniform electric field when it is oriented:
A.
Perpendicular to the field only
B.
At 45° to the field only
C.
Parallel or antiparallel to the field
D.
At 60° to the field only
Correct Answer:
Parallel or antiparallel to the field
Explanation:
Torque is zero when sin θ = 0, which occurs at θ = 0° and 180°. These correspond to parallel and antiparallel orientations.
8. The SI unit of torque acting on an electric dipole is:
A.
N/C
B.
C m
C.
N m
D.
J/C
Correct Answer:
N m
Explanation:
From τ = pE sin θ, the unit of torque is newton metre (N m), which is also equivalent to joule.
9. If the electric field acting on a dipole is doubled while its dipole moment and orientation remain unchanged, the torque becomes:
A.
Half
B.
Unchanged
C.
Double
D.
Four times
Correct Answer:
Double
Explanation:
Since τ = pE sin θ, torque is directly proportional to the electric field E when p and θ are constant. Therefore, doubling E doubles the torque.
10. If the dipole moment of an electric dipole is doubled while the electric field and orientation remain unchanged, the torque becomes:
A.
Half
B.
Unchanged
C.
Double
D.
Four times
Correct Answer:
Double
Explanation:
The torque is τ = pE sin θ. With E and θ constant, torque is directly proportional to p, so doubling the dipole moment doubles the torque.
Short Questions and Answers
Practice short questions and answers related to
Torque on a dipole
.
Short questions are currently unavailable for this page.