Question

In the circuit shown, the ammeter reading is zero. What is the resistance of resistor r

Answer 1

Answer:

the value of the resistor R will be 100Ω

Explanation:

In the circuit , the Ammeter G shows zero deflection. The batteries A and B have negligible internal resistance,

the Ammeter G shows zero deflection , if no current flows through it

so no potential difference across it.

=> Potential difference across R should be 2V

Potential Difference across R =   (R)/(R + 500)  * 12

=> (R)/(R + 500)  * 12 = 2

=> 6R = R + 500

=> 5R = 500

=> R = 100

the value of the resistor R will be 100 Ω