In the circuit, the galvanometer G shows zero deflection. If the batteries A and b have negligible internal resistance, the value of the resistor R will be -

Options

A. `1000 Omega`
B. `500 Omega`
C. `100 Omega`
D. `200 Omega`

Answer

C

Explanation

Current through `R` is `12//(500 + R)`
voltage across `R` is `(12 R)/(500 + R)`
Since galvanometer shows zero deflection, so
`(12 R)/(500 + R) = 2` or `R = 100 Omega`