In the circuit the galvanometer `G` shows zero deflection. If the batteries A and B have negligible internal resistance find the value of the resitor `R`

Answer

`100 Omega`

Explanation

Since gavanometer shows no deflection potential difference across `R = 2V` .Therefore potential difference across `500 Omega = 12 - 2 = 10V`
Current through `500 Omega = (10)/(500) = (1)/(50)A`
As same current flows through `R`
`:. R = ("pot. diff")/("current") = (2)/((1//50)) = 100 Omega`