EASY

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Why the coil of the moving coil galvanometer is wound over an aluminium frame.

Important Questions on Magnetic Effect of Current

EASY

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

The reason a moving coil galvanometer cannot be used with an alternating current is that

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

The galvanometer deflection, when key $K_{1}$ is closed but $K_{2}$ is open, equals $θ_{0}$ (see figure). On closing $K_{2}$ also and adjusting $R_{2}$ to $5 Ω,$ the deflection in galvanometer becomes $\frac{θ_{0}}{5} .$ The resistance of the galvanometer is, then, given by [Neglect the internal resistance of battery]:

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MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

The current sensitivity of a moving coil galvanometer depends on,

EASY

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

Phosphor-bronze wire is used for suspension in a moving coil galvanometer, because it has:

HARD

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

A moving coil galvanometer has 50 turns and each turn has an area

2 \times 10^{- 4} m^{2}

. The magnetic field produced by the magnet inside the galvanometer is

0.02 T

. The torsional constant of the suspension wire is

10^{- 4} N m {rad}^{- 1}

. When a current flows through the galvanometer, a full scale deflection occurs if the coil rotates by

0.2 rad

. The resistance of the coil of the galvanometer is

50 Ω

. This galvanometer is to be converted into an ammeter capable of measuring current in the range

0 - 1.0 A

. For this purpose, a shunt resistance is to be added in parallel to the galvanometer. The value of this shunt resistance, in ohms, is

α

. Write the value of

[α]

, where

[]

is the greatest integer function.

EASY

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

Define current sensitivity of a galvanometer. Write its expression.

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

Current sensitivity of a moving coil galvanometer is

5 d i v / m A

and its voltage sensitivity (angular deflection per unit voltage applied) is

20 d i v / V

. The resistance of the galvanometer is

EASY

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

Write the definition of figure of merit of Galvanometer.

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

A moving coil galvanometer has a coil with

175

turns and area

1 c m^{2} .

It uses a torsion band of torsion constant

10^{- 6} N m / r a d

The coil is placed in a magnetic field B parallel to its plane. The coil deflects by

1^{o}

for a current of

1 m A

The value of B (in tesla) is approximately:

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

The resistance of a galvanometer is

50 o h m

and the maximum current which can be passed through it is

0.002 A .

What resistance must be connected to it in order to convert it into an ammeter of range

0 - 0.5 A ?

HARD

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

State the advantages and disadvantages of a moving coil galvanometer.A moving coil galvanometer (M.C.G.) has

10

10 turns each of length

12 cm

and breadth

8 cm

. The coil of M.C.G. carries a current of

125 μA

and is kept perpendicular to the uniform magnetic field of induction

10^{- 2} T

. The twist constant of phosphor bronze fibre is

12 \times 10^{- 9} Nm / degree

. Calculate the deflection produced.

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

A galvanometer having a coil resistance of

100 Ω

gives a full scale deflection, when a current of

1 mA

is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of

10 A

, is:

HARD

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

What is moving coil galvanometer? Draw labelled diagram of suspended coil galvanometer and prove that the deflection of a coil is directly proportional to the current flowing through it.

EASY

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

A galvanometer of resistance

50 Ω

is connected to battery of

3 V

along with a resistance of

2950 Ω

in series. A full scale deflection of 30 divisions is obtained in the galvanometer. In order to reduce this deflection to

20

divisions, the resistance in series should be

EASY

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

The resistance of a galvanometer is

99 Ω

. The necessary current for full scale deflection is

1 mA

. If a shunt of

1 Ω

is connected with galvanometer then find the value of maximum current which can be measured by this galvanometer.

HARD

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

Explain the working of a moving coil galvanometer. How it can be converted into ammeter?

EASY

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

With the help of a diagram, explain the principle and working of a moving coil galvanometer.

EASY

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

The current sensitivity of moving coil galvanometer of resistance

100 Ω

1 div / mA .

Its voltage sensitivity is

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

To know the resistance

G

of a galvanometer by half deflection method, a battery of emf

V_{E}

and resistance

R

is used to deflect the galvanometer by angle

θ

. If a shunt of resistance

S

is needed to get half deflection the

G

R

and

S

are related by the equation:

EASY

Physics>Electricity and Magnetism>Magnetic Effect of Current>Galvanometer and Its Types

Sensitivity of moving coil galvanometer is

s

. If a shunt of

{(\frac{1}{8})}^{t h}

of the resistance of galvanometer is connected to moving coil galvanometer, its sensitivity becomes

Why the coil of the moving coil galvanometer is wound over an aluminium frame.

Important Questions on Magnetic Effect of Current

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