A galvanometer of resistance G is converted into a voltmeter of range 0 – 1 V by connecting a resistance R1 in series with it. The additional resistance that should be connected in series with R1 to increase the range of the voltmeter to 0 – 2 V will be :
Solution
1 = i<sub>g</sub>(G + R<sub>1</sub>) ....(1)
<br><br>2 = i<sub>g</sub>(R<sub>1</sub> + R<sub>2</sub> + G) ....(2)
<br><br>Doing (1) $\div$ (2), we get
<br><br>$${1 \over 2} = {{{i_g}\left( {G + {R_1}} \right)} \over {{i_g}\left( {G + {R_1} + {R_2}} \right)}}$$
<br><br>$\Rightarrow$ R<sub>1</sub>
+ R<sub>2</sub>
+ G = 2R<sub>1</sub>
+ 2G
<br><br>$\Rightarrow$ R<sub>2</sub>
= R<sub>1</sub>
+ G
About this question
Subject: Physics · Chapter: Current Electricity · Topic: Ohm's Law and Resistance
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