Question

A galvanometer of resistance G can be converted into a voltmeter of range (0-V) volts by connecting a resistance R in series with it. How much resistance will be required to change it from (0-V/2)?

Answer 1

Given: A galvanometer of resistance G can be converted into a voltmeter of range (0-V) volts by connecting a resistance R in series with it.

To find: How much resistance will be required to change it from (0-V/2) ?

Solution:

• Now we know that we can convert a galvanometer to voltmeter by connecting high resistance in series.

• Now we have given a galvanometer of resistance G can be converted into a voltmeter of range (0-V) volts by connecting a resistance R in series with it.

• For voltmeter for range v/2, the resistance will be:

                  V = I(g)( G + R )  

                  v/2 = I(g)( G + r )

                  v/I(g).2 = G + r

                  r = v/2.I(g) - G

Answer:

           So the resistance required is v/2.I(g) - G.

Answer 2

Given that,

Galvanometer = G

Resistance = R

Voltmeter = V

We know that,

A galvanometer can be converted to voltmeter by connecting high resistance in series.

Here, The voltmeter of range V, galvanometer resistance is G and resistance connected is R.

If the voltage $\dfrac{V}{2}$

We need to calculate the resistance

Using formula of voltage

$V=I_{g}(G+R)$

Where, V = voltage

I = current

G =  galvanometer of resistance

R = resistance

Put the value into the formula

$\dfrac{V}{2}=I_{g}(G+R)$

$R=\dfrac{V}{2I_{g}}-G$

Hence, The resistance will be $\dfrac{V}{2I_{g}}-G$