A galvanometer of resistance G is converted into a voltmeter to measure upto V volts by connecting a resistance R 1 in series with the coil. If a resistance R 2 is connected in series with it, then it can measure upto V 2 volts. Find the resistance, in terms of R 1 and R 2 , required to be connected to convert it into a voltmeter that can read upto 2 V . Also find the resistance G of the galvanometer in terms of R 1 and R 2 .

For voltmeter of range V , V = I g G + R 1 ...(i) For voltmeter of range V / 2 , V 2 = I g G + R 2 .....(ii) On dividing (i) by (ii) 2 = G + R 1 G + R 2 or 2 G + R 2 = G + R 1 ∴ G = R 1 − 2 R 2 Let R 3 be the resistance required for conversion into voltmeter of range 2 V . then, 2 V = I g G + R 3 ...(iii) 2 = G + R 3 G + R 1 or 2 G + 2 R 1 = G + R 3 ∴ R 3 = G + 2 R 1 = R 1 − 2 R 2 + 2 R 1 = 3 R 1 - 2 R 2 .

EASY

12th CBSE

IMPORTANT

Earn 100

Define current sensitivity and voltage sensitivity of a galvanometer. Increasing the current sensitivity may not necessarily increase the voltage sensitivity of a galvanometer. Justify.

Important Questions on Magnetic Effect of Current

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>HOTS Problems on Higher Order Thinking Skills>Q 18

An $α$ -particle and a proton are released from the centre of the cyclotron and made to accelerate.

(i) Can both be accelerated at the same cyclotron frequency ? Give reason to justify your answer.

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>HOTS Problems on Higher Order Thinking Skills>Q 18

An $α$ -particle and a proton are released from the centre of the cyclotron and made to accelerate.

(ii) When they are accelerated in turn, which of the two will have higher velocity at the exist slit of the dees ?

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>HOTS Problems on Higher Order Thinking Skills>Q 29

A length

L

of a wire carries a current

I

. Show that if the wire is formed into a circular coil, the maximum torque in a given magnetic field is developed when the coil has one turn only and the maximum torque has the value,

τ = L^{2} I B / 4 π

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>HOTS Problems on Higher Order Thinking Skills>Q 32

A galvanometer is shunted by

1 / n

th of its resistance. Find the fraction of the total current passing through the galvanometer.

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>HOTS Problems on Higher Order Thinking Skills>Q 33

If a galvanometer is connected in series with a high resistance so that potential drop across the galvanometer is

1 / n

th of the total applied voltage, then show
that the combined resistance of the galvanometer and the series resistor is n times the resistance of the galvanometer i.e.,

R_{V} = n R_{g}

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>HOTS Problems on Higher Order Thinking Skills>Q 34

A galvanometer of resistance

G

is converted into a voltmeter to measure upto

V

volts by connecting a resistance

R_{1}

in series with the coil. If a resistance

R_{2}

is connected in series with it, then it can measure upto

\frac{V}{2}

volts. Find the resistance, in terms of

R_{1}

and

R_{2}

, required to be connected to convert it into a voltmeter that can read upto

2 V

. Also find the resistance

G

of the galvanometer in terms of

R_{1}

and

R_{2}

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>GUIDELINES TO NCERT EXERCISES>Q 4.2.

A long straight wire carries a current of

35 A

. What is the magnitude of the field

B

at a point

20 cm

from the wire? Take,

μ_{0} = 4 π \times 10^{- 7} H / m

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 4 - Magnetic Effect of Current>GUIDELINES TO NCERT EXERCISES>Q 4.3.

A long straight wire in the horizontal plane carries a current of

50 A

in the north to south direction. Give the magnitude and direction of

B

at a point

2.5 m

east of the wire. Take,

μ_{0} = 4 π \times 10^{- 7} H / m

Define current sensitivity and voltage sensitivity of a galvanometer. Increasing the current sensitivity may not necessarily increase the voltage sensitivity of a galvanometer. Justify.

Important Questions on Magnetic Effect of Current

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