When a coil of magnetic moment 3 . 0 × 10 - 8 amp - m 2 is placed in a magnetic field such that its plane is parallel to the field, then the moment of the couple acting on the coils is 7 . 5 × 10 - 9 N - m . Find the magnitude of the magnetic field. What shall be the value of current flowing in it if the area of the coil is 1 . 5 cm 2 and the number of turns is 15 ?

Magnetic moment is M = mL m = M L ∵ F = mB F = M L B L = MB F Given, Capacitance C = 50 pF Also, C = KAε ∘ d Dielectric constant of material, K = 3 ∴ A = Cd ε ∘ K = 50 × 10 − 12 × 10 − 3 8 . 85 × 10 − 12 × 3 ≈ 19 cm 2

EASY

12th Uttar Pradesh Board

IMPORTANT

Earn 100

A flat circular coil of radius $3.0 cm$ has $100$ turns. A current of $2.0 amp$ is passed through it. Calculate the magnetic field at a point on the axis of the coil of a distance of $4.0 cm$ from its centre.

Important Questions on Moving Charges and Magnetism

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12th Uttar Pradesh Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 4 - Moving Charges and Magnetism>Uttar Pradesh Board-2018>Q 5

State Biot-Savart's law. A current of

5

ampere is flowing through a circular loop of radius

10 cm

. Calculate the magnetic field at the centre of the loop.

EASY

12th Uttar Pradesh Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 4 - Moving Charges and Magnetism>Uttar Pradesh Board-2019>Q 6

Obtain the formula of coefficient of self-induction of a current carrying solenoid.

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12th Uttar Pradesh Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 4 - Moving Charges and Magnetism>Uttar Pradesh Board-2019>Q 7

A Galvanometer is of $50 Ω$ resistance and current for full scale deflection is $0.05 A$ . What length of the shunt will be required so as to convert the galvanometer into an ammeter of $5 A$ range?

Area of cross-section of wire $= 2.97 \times 10^{- 2} {cm}^{2}$ . Specific resistivity of the wire material $= 5 \times 10^{- 7} Ωm$ .

MEDIUM

12th Uttar Pradesh Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 4 - Moving Charges and Magnetism>Uttar Pradesh Board-2019>Q 8

What is Ampere's circuit law? Derive the formula of magnetic field inside a current carrying solenoid with its help.

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12th Uttar Pradesh Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 4 - Moving Charges and Magnetism>Uttar Pradesh Board-2019>Q 9

A wire of length

L

is turned in the form of a circular coil of

N

turns and then suspended in a magnetic field

B

. If

i

current is passed in the coil, then obtain the formula for the maximum torque acting on the coil.

EASY

12th Uttar Pradesh Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 4 - Moving Charges and Magnetism>Uttar Pradesh Board-2020>Q 10

The resistance of the required shunt in order to pass

10 %

of the main current in a galvanometer of

99 Ω

resistance should be

MEDIUM

12th Uttar Pradesh Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 4 - Moving Charges and Magnetism>Uttar Pradesh Board-2020>Q 11

Write down the vector form of Lorentz force acting on a moving charge in a uniform magnetic field. Two particles

A

and

B

having same charge after being accelerated by the same accelerating potential, enter perpendicular in a uniform magnetic field, so that they

R_{1}

and

R_{2}

respectively. Find out the ratio of the masses of

A

and

B

in terms of

R_{1}

and

R_{2}

A flat circular coil of radius 3.0 cm has 100 turns. A current of 2.0 amp is passed through it. Calculate the magnetic field at a point on the axis of the coil of a distance of 4.0 cm from its centre.

Important Questions on Moving Charges and Magnetism

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A flat circular coil of radius $3.0 cm$ has $100$ turns. A current of $2.0 amp$ is passed through it. Calculate the magnetic field at a point on the axis of the coil of a distance of $4.0 cm$ from its centre.