The range of an ammeter of resistance G can be increased from I to n I by connecting

A series resistance of G n + 1 Ω

A series resistance of G n - 1 Ω

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Out of the two, an ammeter or a milliammeter, ammeter has a higher resistance.

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Important Questions on Moving Charges and Magnetism

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

A galvanometer has a 50 division scale. Battery has no internal resistance. It is found that there is deflection of 40 divisions when $R.B. = 2400 Ω .$ Deflection becomes 20 divisions when resistance taken from resistance box is 4900 Ω. Then we can conclude :

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EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

A galvanometer with its coil resistance

25 Ω

requires a current of

1 mA

for its full deflection. In order to construct an ammeter to read up to a current of

2 A

the approximate value of the shunt resistance should be:

HARD

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

In a circuit for finding the resistance of a galvanometer by half deflection method, a

6 V

battery and a high resistance of

11 kΩ

are used. The figure of merit of the galvanometer is

60 μA {division}^{- 1}

. In the absence of shunt resistance, the galvanometer produces a deflection of

θ = 9

divisions when current flows in the circuit. The value of the shunt resistance that can cause the deflection of

\frac{θ}{2}

, is closest to:

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

In an ammeter

0.2 %

of main current passes through the galvanometer. If resistance of galvanometer is

G,

the resistance of ammeter will be:

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

How is a galvanometer converted to an ammeter?

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

A moving coil galvanometer, having a resistance

G,

produces full scale deflection when a current

I_{G}

flows through it. This galvanometer can be converted into (i) an ammeter of range 0 to

I_{o} (I_{0} > I_{g})

by connecting a shunt resistance

R_{A}

to it and (ii) into a voltmeter of range 0 to

V (V = G I_{0})

by connecting a series resistance

R_{V}

to it. Then,

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

This question has

Statement I

and

Statement II

. Of the four choices given after the Statements, choose the one that best describes the two Statements.

Statement - I :

Higher the range, greater is the resistance of ammeter.

Statement - II :

To increase the range of ammeter, additional shunt needs to be used across it.

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

A galvanometer of resistance

100 Ω

requires

10 μA

current for full scale deflection. Now a resistance of

1 Ω

is connected to convert it into an ammeter. The minimum current required to obtain full scale deflection is

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

Derive the expression for the torque acting on the rectangular current carrying coil of a galvanometer. Why is the magnetic field made radial?

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

Define current sensitivity of a galvanometer. Write its expression.

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

The range of an ammeter of resistance

G

can be increased from

I

n I

by connecting

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

How do you convert a moving coil galvanometer into an ammeter?

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

The deflection in galvanometer falls to $\left(\frac{1}{4}\right)^{\operatorname{th}}$ when it is shunted by $3 Ω$ . If additional shunt of $2 Ω$ is connected to earlier shunt, the deflection in galvanometer falls to

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

50 Ω

resistance is connected to a battery of

5 V

. A galvanometer of resistance

100 Ω

is to be used as an ammeter to measure current through the resistance, for this a resistance

r_{S}

is connected to the galvanometer. Which of the following connections should be employed if the measured current is with in

1 %

of the current without the ammeter in the circuit?

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

An ammeter of resistance

1.5 Ω

can measure currents upto

1 A

. The value of shunt resistance to measure current upto

4 A

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

50 ohm

galvanometer gets full scale deflection when a current of

0.01 A

pass through the coil. When it is converted to a

10 A

ammeter, the shunt resistance is

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

A galvanometer having a resistance of

8 Ω

is shunted by a wire of resistance

2 Ω .

If the total current is

1 A,

the part of it passing through the shunt will be

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

A circuit contains an ammeter, a battery of 30 v and a resistance 40.8 ohm all connected in series. If the ammeter has coil of resistance 480 ohm and a shunt of 20 ohm, the reading in the ammeter will be:

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

Distinguish between ammeter and voltmeter.

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Physics>Electricity and Magnetism>Moving Charges and Magnetism>Electrical Instruments

When a current of

5 mA

is passed through a galvanometer having a coil of resistance

15 Ω

, it shows full-scale deflection. The value of the resistance to be put in series with the galvanometer to convert it into a voltmeter of range

0 - 10 V

is:

Out of the two, an ammeter or a milliammeter, ammeter has a higher resistance.

Important Questions on Moving Charges and Magnetism

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