10 MCQs| PHYSICS| CLASS XII | MAGNETISM AND MATTER

1. Which of the following statements is/are True?

Statement I- The earth behaves as a magnet with the magnetic field pointing exactly from the geographic south to the north

Statement II- Magnetic monopoles do not exist.

Statement III-  It is possible to make magnets out of iron and its alloys.

a) I and II

b) I, II and III

c) II and III

d) III only 

Answer

Answer : c

2. Which of the following statements is/are True?

Statement I- The magnetic field lines escape to infinity

Statement II- Magnetic field lines of a solenoid form continuous closed loops.

Statement III-  The tangent to the field line at a given point represents the direction of the net magnetic field B at that point.

a) I and II

b) I, II and III

c) II and III

d) III only 

 

Answer

Answer : b

3. Magnetic moment of a solenoid at a far away axial point is ____________.

Answer

Answer : a

4. The magnetic potential energy of a magnetic dipole is 

a) minimum at θ=180°

b) maximum at θ=0°

c) maximum at θ=180°

d)  minimum at θ=90

Answer

Answer : c

5.  A magnetic needle has magnetic moment 6.7 × 10^–2 Am² and moment of inertia I = 7.5 × 10^–6 kg  

     m² . It performs 10 complete oscillations in 6.70 s in the presence of a magnetic field. What is the 

     magnitude of the magnetic field?

a) 10^-2G

b) 10²G

c) 10^-3G

d) 10³G

Answer

Answer : B

6. A short bar magnet placed with its axis at 30° with an external field of 800 G experiences a torque of 0.016 Nm. What is the work done in moving it from its most stable to most unstable position?

a) 0.064 J 

b) 0.64 J 

c)  6.4 J

d)  64 J

 

Answer

Answer : a

7. A magnetized needle is placed in a magnetic field. What will happen to it ?

a) It will experience Force as well as Torque if field is uniform.

b) It will experience only Force if Field is non uniform.

c) It will neither experience Torque nor Force irrespective of the field.

d) It will experience Force as well as Torque if field is non uniform.

Answer

Answer : d

8. Which of the following statements is True about Toroid ?

a) It has a magnetic South and North Pole.

b) It has net  non-zero magnetic moment.

c) It has zero magnetic moment

d) None of the above

Answer

Answer : c

9. Which of the following diagrams represent correct magnetic field lines ?

Answer

Answer : c

10. The earth’s magnetic field at the equator is approximately 0.4 G. Estimate the earth’s dipole moment.

a) 1.05 × 10²³ A m²

b) 1.05 × 10^-23 A m²

 c)1.05 × 10²⁴ A m²

d)1.05 × 10^-24 A m²

 

Answer

Answer : a

For the following diagram, answer the questions from Q11 to Q13

11. Which of the following systems is not in equilibrium?

a) PQ1

b) PQ3

c) PQ4

d) PQ6

 

Answer

Answer : a

12. Which of the following is in unstable equilibrium ?

a) PQ2

b) PQ3

c) PQ5

d) PQ6

 

Answer

Answer : c

13. Which of the following systems has highest potential energy?

a) PQ1

b) PQ3

c) PQ4

d) PQ6

 

Answer

Answer : c

14. Which of the following statements is incorrect with regard to magnetic field lines ?

a) Magnetic field lines can never emanate from a point.

b) Field lines due to solenoid at its end should curve out and meet eventually to form closed loops.

c) Magnetic field lines between two pole pieces can not be precisely straight at its ends.

d) The direction of field lines is ambiguous at the point of intersection of two such lines.

 

Answer

Answer : d

For questions from 15 to 17 , answer as per the options below:

a) Assertion is True, Reason is True ; Reason is correct explanation of assertion.

b) Assertion is True, Reason is True ; Reason is not the correct explanation of assertion.

c) Assertion is True, Reason is False

d) Assertion is False, Reason is True

15. Assertion: Magnetic field lines show the direction (at every point) along which a small magnetized  

      needle aligns (at the point)

      Reason: Magnetic field lines also represent the lines of force on a moving charged particle at every  

      point

Answer

Answer : c

16. Assertion: One element of a current-carrying wire exert a force on another element of the same 

      wire

      Reason: For the special case of a straight wire, this force is zero

Answer

Answer : b

17. Assertion: The pole near the geographic north pole is called north magnetic pole.

      Reason: The north pole of the magnet was so named as it was the north seeking pole.

Answer

Answer : b

18. The vertical plane which passes through the imaginary line joining the magnetic north and the south poles is called ____________.

a) Magnetic meridian

b) Geographic Meridian

c) Equator

d) None of the above

Answer

Answer : a

19.