MEDIUM

Earn 100

In the circuit figure, the voltmeter reads $30 V$ . The resistance of the voltmeter is

50% studentsanswered this correctly

Important Questions on Magnetic Fields due to Electric Current

MEDIUM

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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:

EASY

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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:

EASY

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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

EASY

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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:

EASY

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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

MEDIUM

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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 :

Question Image

Note: This question is awarded as the bonus. Now the question is corrected.

EASY

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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:

MEDIUM

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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 Fields due to Electric Current>Voltmeter

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]:

Question Image

EASY

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

A

B

and

C

are voltmeters of resistance

R

1 .5 R

and

3 R

respectively as shown in the figure. When some potential difference is applied between

X

and

Y

, the voltmeter readings are

V_{A}, V_{B}

and

V_{C}

respectively. Then:
Question Image

MEDIUM

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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?

MEDIUM

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

A galvanometer, whose resistance is

50 ohm

, has

25

divisions in it. When a current of

4 \times 10^{- 4}

A passes through it, its needle (pointer) deflects by one division. To use this galvanometer as a voltmeter of range

2.5 V

it should be connected to a resistance of:

HARD

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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,

MEDIUM

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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:

HARD

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

A galvanometer of resistance

100 Ω

has

50

divisions on its scale and has sensitivity of

20 μ A / d i v i s i o n

. It is to be converted to voltmeter with three ranges, of

0 - 2 V, 0 - 10 V

and

0 - 20 V .

The appropriate circuit to do so is:

MEDIUM

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

A moving coil galvanometer has resistance

50 Ω

and it indicates full deflection at

4 m A

current. A voltmeter is made using this galvanometer and a

5 k Ω

resistance. The maximum voltage, that can be measured using this voltmeter, will be close to:

MEDIUM

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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 Fields due to Electric Current>Voltmeter

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:

EASY

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

10 V

battery with internal resistance

1 Ω

and a

15 V

battery with internal resistance

0.6 Ω

are connected in parallel to a voltmeter (see figure). The reading in the voltmeter will be close to:

Question Image

EASY

Physics>Electricity and Magnetism>Magnetic Fields due to Electric Current>Voltmeter

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.

In the circuit figure, the voltmeter reads 30 V. The resistance of the voltmeter is

Important Questions on Magnetic Fields due to Electric Current

Learn and Prepare for any exam you want !

In the circuit figure, the voltmeter reads $30 V$ . The resistance of the voltmeter is