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A galvanometer coil has a resistance of $12 \Omega$ and the metre shows full scale deflection for a current of 3 mA. How will you convert the metre into a voltmeter of range 0 to 18 V?
A galvanometer coil has a resistance of $12 \Omega$ and the metre shows full scale deflection for a current of 3 mA. How will you convert the metre into a voltmeter of range 0 to 18 V?
CBSE | Class 12 | Moving Charges and Magnetism | NCERT | Physics
A galvanometer coil has a resistance of $12 \Omega$ and the metre shows full scale deflection for a current of 3 mA. How will you convert the metre into a voltmeter of range 0 to 18 V?

Resistance of the galvanometer coil is given as $G=12 \Omega$

Current for which there is full scale deflection is given as I $=3 \mathrm{~mA}$

To convert a galvanometer to voltmeter,
a resistor with a resistance $R$ is connected in series. The resistance $R$ is given as

$R=(V / I g)-G$

$=\frac{18}{3 \times 10^{-3}}-12=6000-12=5988 \Omega$

By connecting a resistor of $5988 \Omega$, a galvanometer can be converted into a voltmeter

i

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