A galvanometer has a current sensitivity of 1 ~mA per division. A variable shunt is connected across the galvanometer and the combination is put in series with a resistance of 500 and cell of internal resistance 1 . It gives a deflection of 5 division for shunt of 5 ohm and 20 division for shunt of 25 ohm . The emf of cell is

Step-by-step solution

Here, I= E R+r+ G S G+S and I_g= I S G+S aligned & I_g= E (R+r)+ G S (G+S) S (G+S) & I_g= E S (R+r)(G+S)+G S aligned For S=5 ohm , I_g=5 10⁻³ ~A and for S=25 ohm I_g=20 10⁻³ ~A Hence, 5 10⁻³= E 5 501(G+5)+5 G and 20 10⁻³= E 25 501(G+25)+25 G Dividing and solving, G=88.2 From (i), we get aligned E & =10⁻³[501(88.2+5)+5 88.2] & =47.1 volt aligned