In the circuit shown below, the ammeter reading is zero. Then, the value of the resistance R is

Options

A. `50 Omega`
B. `100 Omega`
C. `200 Omega`
D. `400 Omega`

Answer

B

Explanation

Given that

In loop (1)
`12 - 500 i_1 = Ri_1 = 0`
`implies 12 = i_1 (500 + R).....(i)`
In loop (2) `12 - 500 i_1 - 2 = 0`
`implies 10 = 500 i_i`
or `i_1 = 1/50 A " "....(ii)`
From equations (i) and (ii)
`12 xx 1/(i_1) = (500 + R)`
`implies 12 xx 50 = 500 xx R`
`implies R = 100 Omega`