The current sensitivity of a galvanometer having 20 divisions is 10 A / div. If the resistance of the galvanometer is 100 then the value of the resistance to be used to convert this galvanometer in to an voltmeter to read up to 1 ~V is :

Step-by-step solution

The full scale deflection current I_g of the galvanometer is calculated by multiplying the number of divisions by the current sensitivity per division. I_g = 20 divisions 10 A/div = 200 A = 200 10⁻⁶ A = 2 10⁻⁴ A . To convert a galvanometer into a voltmeter, a high resistance R must be connected in series with the galvanometer. The formula for the total resistance is V = I_g(R + G) , where V is the voltage to be measured and G is the resistance of the galvanometer. Given V = 1 V and G = 100 , we have 1 = 2 10⁻⁴ (R +