Question

The maximum current in a galvanometer can be $10mA$. Its resistance is $10\Omega$. To convert it into an ammeter of 1 Amp. a resistor should be connected in.

• A. series, $0.1\Omega$
• B. parallel, $0.1\Omega$
• C. $series,100\Omega$
• D. $parallel,100\Omega$

Answer 1

The correct option is B parallel, $0.1\Omega$

Current in Galvanometer, $I_g=10mA={10}^{-2}mA$

Resistance of Galvanometer, G = 10 Ohm

Current of Ammeter, $I_a=1A$

To convert a Galvanometer into an Ammeter, a Shunt resistor S is connected in parallel whose value is given as

$S=\frac{I_{g}G}{I-I_g}$

= $\frac{{10}^{-2}\ast 10}{1}=0.1Ohm$

Hence in order to convert Galvanometer into an Ammeter of 1A current a resistance of 0.1 Ohm is connected in parallel.

Option B