R4RIN – MCQs, Mock Tests | NCERT Class 12 MCQ Questions for Class 12 Physics Chapter 4 Moving Charges and Magnetism

The current sensitibility of a moving coil galanometer increases with decrease in:

1. magnetic field
2. area of a coil
3. number of turns
4. None of the above

✅ Correct Answer: 4

A current carring coil is placed in a uniform magnetic field. If the coil turns through an angle θ, then the torque is directly proportional to:

1. sin θ
2. cos θ
3. cot θ
4. tan θ

✅ Correct Answer: 2

The sensitivity of a tangent galvanometer can be increased by increasing:

1. the radius of the coil
2. the external magnetic field
3. the number of turns of the coil
4. all the above

✅ Correct Answer: 2

The permeability of a paramagnetic substance is:

1. very large
2. small but more than unity
3. less than unity
4. negative

✅ Correct Answer: 2

Which of the following shows that the earth behaves as a magnet?

1. Repulsion between like poles .
2. Attraction between unlike poles
3. Null points in the magnetic field of a bar magnet
4. No existence of isolated magnetic poles

✅ Correct Answer: 3

What is the angle of dip at the magnetic poles ?

1. 30°
2. 0°
3. 45°
4. None of the above

✅ Correct Answer: 4

Circular loop of radius 0.0157 m carries a current 2 A. The magnetic field at the centre of the loop is :

1. 1.57 × 10-3Wb/m²
2. 8.0 × 10-5 Wb/m²
3. 2.0 × 10-3 Wb/m²
4. 3.l4 × 10-1 Wb/m²

✅ Correct Answer: 2

What happens to the magnetic field at the centre of a circular current carrying coil if we double the radius of the coil keeping the current unchanged?

1. halved
2. doubled
3. quadrupled
4. remains unchanged

✅ Correct Answer: 1

When we double the radius of a coil keeping the current through it unchanged, what happens to the magnetic field directed along its axis at far off points?

1. halved
2. doubled
3. quadrupled
4. remains unchanged

✅ Correct Answer: 4

The strength of the magnetic field around an infinite current carrying conductor is :

1. same everywhere
2. inversely proportional to the distance
3. directly proportional to the distance
4. None of the above

✅ Correct Answer: 2

same everywhere

1. same everywhere
2. inversely proportional to the distance
3. directly proportional to the distance
4. None of the above

✅ Correct Answer: 2

A current carrying power line carries current from west to east. Then the direction of the magnetic field 2 m above it is :

1. west to east
2. south to north
3. north to south
4. None of the above

✅ Correct Answer: 3

The force between two parallel current carrying conductors is F. If the current in each conductor is doubled, then the force between them becomes :

1. 4F
2. 2F
3. F
4. F/4

✅ Correct Answer: 1

Which of the following is not a unit of magnetic induction?

1. gauss
2. tesla
3. oersted
4. weber/metre²

✅ Correct Answer: 3

A charge + q is sent through a magnetic field. The force acting on it is maximum w hen the angle between the direction of motion of the charged particle and the magnetic field :

1. 0°
2. 45°
3. 90°
4. 180°

✅ Correct Answer: 3

A wire of length 2 metre carries a current 1 ampere, is bent to form a circle. The magnetic moment of the coil is :

1. 2π
2. π/2
3. π/4
4. 1/π

✅ Correct Answer: 4

The magnetic field of a given length of a ware for single turn coil at its centre is B. Then.its value for two turns of coil will be :

1. B/4
2. B/2
3. 4B
4. 2B

✅ Correct Answer: 3

When charged particle enters-a uniform magnetic field, its K.E.:

1. remains constant
2. increases
3. decreases
4. becomes zero

✅ Correct Answer: 1

To convert galvanometer into voltmeter one should connect :

1. high resistance in series with galvanometer
2. low resistance in series with galvanometer
3. high resistance in parallel with galvanometer
4. low resistance in parallel with galvanometer

✅ Correct Answer: 1

Isoclinic lines are the lines joining places with :

1. equal dip
2. equal declination
3. equal dip and declination
4. None of the above

✅ Correct Answer: 1

The most suitable metal for making permanent magnets is :

1. iron
2. steel
3. copper
4. aluminium

✅ Correct Answer: 2

The SI unit of magnetic dipole moment is’

1. Ampere
2. Ampere metre²
3. Tesla
4. None of the above

✅ Correct Answer: 2

Earth’s magnetism was discovered by:

1. Gauss
2. Oersted
3. Ampere
4. Gilbert

✅ Correct Answer: 4

According to Gauss’s theorem in magnetism, surface integral of magnetic field intensity over a surface (closed or open) is always:

1. -1
2. 1
3. 0
4. infinity

✅ Correct Answer: 3

Tesla is a unit of:

1. electric flux
2. magnetic flux
3. magnetic field
4. electric field

✅ Correct Answer: 3

10 eV electron is circulating in a plane at right angle to a uniform field of magnetic induction 10-1 Wb/m² (1G). The orbital radius of electron is:

1. 12 cm
2. 16 cm
3. 11 cm
4. 18 cm

✅ Correct Answer: 3

A cyclotron can be used to produce high energy:

1. neutrons
2. deutrons
3. β particles
4. α partifcles

✅ Correct Answer: 4

The radius of the trajectory of a charged particle in a uniform magnetic field is proportional to the:

1. charge on the particle
2. energy of the particle
3. momentum of the particle
4. All the above

✅ Correct Answer: 2