A moving coil galvanometer of resistance G gives a full scale deflection for a current I g Use the suitable circuit diagram to convert it into an ammeter of range 0 to I I > I g . Deduce the expression for the shunt required for this conversion. Hence write the expression for the resistance of the ammeter thus obtained.

Given: The resistance of galvanometer, = G Current in galvanometer for full-scale deflection, I g The range of ammeter, 0 to I Let the required shunt resistance is S and the current through the shunt is I - I g The shunt resistance is connected in parallel with the galvanometer. Hence, P.D. across the galvanometer = P.D. across the shunt I g G = I - I g S ⇒ S = I g I - I g × G Now the total resistance of ammeter, R A = G S G + S < S

EASY

12th CBSE

IMPORTANT

Earn 100

Draw a schematic sketch of a cyclotron. Explain clearly the role of crossed electric and magnetic fields in accelerating the charge. Hence derive the expression for the kinetic energy acquired by the particles.

Important Questions on Magnetic Effect of Current

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>Text Based Exercises>Q 22

Derive an expression for the maximum force experienced by a straight conductor of length

l

, carrying current

I

and kept in a uniform magnetic field,

B

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>Text Based Exercises>Q 23

Two long straight parallel conductors carry steady currents

I_{1}

and

I_{2}

separated by a distance

d

. If the currents are flowing in the same direction, show how the magnetic field set-up in one produces an attractive force on the other. Obtain the expression for this force. Hence define one ampere.

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>Text Based Exercises>Q 24

Derive a formula for the force between two parallel straight conductors carrying current in opposite directions and write the nature of the force. Hence, define an ampere.

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>Text Based Exercises>Q 25

Derive an expression for the torque on a rectangular coil of area

A

, carrying a current

I

and placed in a magnetic field

B

. The angle between the direction of

B

and vector perpendicular to the plane of the coil is

θ

. Indicate the direction of the torque acting on the loop.

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>Text Based Exercises>Q 28

State the principle of a moving coil galvanometer. Show that the current passing through the coil is directly proportional to the deflection of the coil.

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>Text Based Exercises>Q 29

A moving coil galvanometer consists of a rectangular coil of

N

turns, each of area

A

, suspended in a radial magnetic field of flux density

B

. Derive the expression for the torque on the coil, when current

I

passes through it. Draw a suitable labelled diagram.

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>Text Based Exercises>Q 30

A moving coil galvanometer of resistance

G

gives a full scale deflection for a current

I_{g}

Use the suitable circuit diagram to convert it into an ammeter of range

0

I (I > I_{g})

. Deduce the expression for the shunt required for this conversion. Hence write the expression for the resistance of the ammeter thus obtained.

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>Text Based Exercises>Q 31

Explain how will you convert a galvanometer into a voltmeter to read a maximum potential difference of

V

volts. Can one use a voltmeter to measure the emf of a cell? Justify your answer.

Draw a schematic sketch of a cyclotron. Explain clearly the role of crossed electric and magnetic fields in accelerating the charge. Hence derive the expression for the kinetic energy acquired by the particles.

Important Questions on Magnetic Effect of Current

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