A potentiometer is used to measure the potential difference between A and B , the null point is obtained at 0.9 ~m . Now potential difference between A and C is measured, the null point is obtained at 0.3 ~m . The ratio E₂ E₁ is (E₁>E₂ )

Step-by-step solution

Position of null point is directly proportional to the potential drop, as the resistance of the wire is directly proportional to the length of the wire. aligned & V_ A B V_ A C = 0.9 ~m 0.3 ~m = E₁ E₁-E₂ & E₁ E₁-E₂ =3---(1) aligned Subtract one from each side of equation (1) aligned & E₁ E₁-E₂ -1=3-1 & E₂ E₁-E₂ =2---(2) aligned Take the ratio of equation (2) and (1), E₂ E₁ = 2 3