EASY

Earn 100

Why is voltmeter always connected in parallel circuits?

Important Questions on Moving Charges and Magnetism

HARD

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

Two identical moving coil galvanometer have

10 Ω

resistance and full scale deflection at

2 μ A

current. One of them is converted into a voltmeter of

100 m V

full scale reading and the other into an Ammeter of

1 m A

full scale current using appropriate resistors. These are then used to measure the voltage and current in the Ohm's law experiment with

R = 1000 Ω

resistor by using an ideal cell. Which of the following statement(s) is/are correct?

MEDIUM

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

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:

EASY

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

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>Moving Charges and Magnetism>Electrical Instruments

A moving coil galvanometer allows a full scale current of

10^{- 4} A

. A series resistance of

2 \times 10^{4} Ω

is required to convert the galvanometer into a voltmeter of range

0 - 5 V

. Therefore, the value of shunt resistance required to convert the above galvanometer into an ammeter of range

0 - 10 m A

is:

MEDIUM

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

Distinguish between ammeter and voltmeter.

MEDIUM

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

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:

EASY

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

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

MEDIUM

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

A galvanometer of resistance $50 Ω$ giving full scale deflection for a current of $10$ milliampere is to be changed into a voltmeter of range $100 V$ .

A resistance of _____ $Ω$ has to be connected in series with the galvanometer.

MEDIUM

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

How is a galvanometer converted to an ammeter?

MEDIUM

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?

HARD

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

A galvanometer having a coil resistance

100 Ω

gives a full scale deflection when a current of

1 m A

is passed through it. What is the value of the resistance which can convert this galvanometer into a voltmeter given full scale deflection for a potential difference of

10 V ?

EASY

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:

HARD

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

A galvanometer can be converted to a voltmeter of full scale deflection

V_{0}

by connecting a series resistance

R_{1}

and can be converted to an ammeter of full scale deflection

I_{0}

by connecting a shunt resistance

R_{2} .

What is the current flowing through the galvanometer at its full scale deflection ?

HARD

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

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:

HARD

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

A student uses the resistance of a known resistor ( $1 Ω$ ) to calibrate a voltmeter and an ammeter using the circuits shown below. The student measures the ratio of the voltage to current to be $1 \times 10^{3} Ω$ in circuit
(a) and $0.999 Ω$ in circuit (b). From these measurements, the resistance (in $Ω$ ) of the voltmeter and ammeter are found to be close to

Question Image

MEDIUM

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

For full scale deflection of total

50

divisions,

50 mV

voltage is required in galvanometer. The resistance of galvanometer if its current sensitivity is

2 div / mA

will be:

EASY

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

A galvanometer coil has a resistance of

10 Ω

and the meter shows full scale deflection for a current of

2 mA .

What resistance needs to be connected to convert the meter into a voltmeter of range

0

18 V ?

EASY

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

Define current sensitivity of a galvanometer. Write its expression.

MEDIUM

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

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

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:

Why is voltmeter always connected in parallel circuits?

Important Questions on Moving Charges and Magnetism

Learn and Prepare for any exam you want !