(C) The current for full-scale deflection ($20$ divisions) is given by $I_1 = \frac{V}{R_g + R_1} = \frac{2}{30 + 1970} = \frac{2}{2000} = 1 \times 10

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(C) The current for full-scale deflection ($20$ divisions) is given by $I_1 = \frac{V}{R_g + R_1} = \frac{2}{30 + 1970} = \frac{2}{2000} = 1 \times 10^{-3} \text{ A} = 1 \text{ mA}$.Since the deflection $\theta$ is directly proportional to the current $I$ $(\theta \propto I)$,to reduce the deflection from $20$ divisions to $10$ divisions,the current must be halved.Thus,$I_2 = \frac{I_1}{2} = 0.5 \times 10^{-3} \text{ A}$.Let the new total series resistance be $R_{total}$. Then $I_2 = \frac{V}{R_g + R_{total}}$.$0.5 \times 10^{-3} = \frac{2}{30 + R_{total}}$.$30 + R_{total} = \frac{2}{0.5 \times 10^{-3}} = 4000 \Omega$.$R_{total} = 4000 - 30 = 3970 \Omega$.

Class 12 Physics Moving Charges and Magnetism The Moving Coil Galvanometer (Sensitivity) and Ammeter and Voltmeter Conversion

Medium

$A$ galvanometer of resistance $30 \Omega$ is connected to a battery of emf $2 \text{ V}$ with $1970 \Omega$ resistance in series. $A$ full-scale deflection of $20$ divisions is obtained in the galvanometer. To reduce the deflection to $10$ divisions,the total resistance in series required is: (in $Omega$)

MHT CET 2016 All MHT CET

A
$4030$
B
$4000$
C
$3970$
D
$2000$

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Class 12

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Chapter

Moving Charges and Magnetism

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The Moving Coil Galvanometer (Sensitivity) and Ammeter and Voltmeter Conversion

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When a resistance of $5\,\Omega$ is shunted with a moving coil galvanometer,it shows a full scale deflection for a current of $250\,mA$. However,when a $1050\,\Omega$ resistance is connected with it in series,it gives full scale deflection for $25\,V$. The resistance of the galvanometer is $......\,\Omega$.

DifficultJEE MAIN 2023

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The pole pieces of the magnet used in a pivoted coil galvanometer are

Easy

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$A$ galvanometer coil has a resistance $80 \Omega$ and current for full-scale deflection is $10 \text{ mA}$. $A$ resistance of $920 \Omega$ is connected in series with the galvanometer to make a voltmeter. If the least count of the voltmeter is $0.2 \text{ V}$,the number of divisions on the scale is:

MediumMHT CET 2025

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When a shunt of $4\,\Omega$ is attached to a galvanometer,the deflection reduces to $\frac{1}{5}$th of its initial value. If an additional shunt of $4\,\Omega$ is attached in parallel to the first,what will be the new deflection?

Difficult

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$A$ galvanometer gives full scale deflection with $0.006 \ A$ current. By connecting it to a $4990 \ \Omega$ resistance,it can be converted into a voltmeter of range $0-30 \ V$. If connected to a $\frac{2n}{249} \ \Omega$ resistance,it becomes an ammeter of range $0-1.5 \ A$. The value of $n$ is:

DifficultIIT 2014

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The pole pieces of the magnet used in a pivoted coil galvanometer are

When a shunt of $4\,\Omega$ is attached to a galvanometer,the deflection reduces to $\frac{1}{5}$th of its initial value. If an additional shunt of $4\,\Omega$ is attached in parallel to the first,what will be the new deflection?

$A$ galvanometer gives full scale deflection with $0.006 \ A$ current. By connecting it to a $4990 \ \Omega$ resistance,it can be converted into a voltmeter of range $0-30 \ V$. If connected to a $\frac{2n}{249} \ \Omega$ resistance,it becomes an ammeter of range $0-1.5 \ A$. The value of $n$ is:

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