Question

A resistance of potentiometer wire is 8 ohm and it's length is 8 m . A resistance box and a 2v battery are connected in series with it. What should be the resistance in box if it desire have a potential drop of micro volume / mm

Answer 1

Hello friend,

here is your answer ;-

Solution :

We have by ohm's law

I=εR=120R

But I=Kθ by theory of galvanometer,

When I=10−6A,θ=1,∴K=10−6

∴10−6θ=120R or R=120×10640=3mΩ

Putting θ=0,5,10,15,20,25,30,35,40 we have the entire scals as ∞

24,12,8,6,4,8,4,3.43 and 3mΩ's