In the given circuit, the ratio of voltmeter reading to the ammeter reading is `R'`. If resistance of ammeter is `RA` and that of voltmeter `RV`, then

Options

A. `R = R' + R_(A)`
B. `R = R' - R_(A)`
C. `R_(v) = R + R_(A)`
D. `R_(v) = R - R_(A)`

Answer

B

Explanation

(b) Let current through `R` is `I_(0)` and voltmeter reading is `V_(0)` then `R' = V_(0)//I_(0)`, Also `V_(0) = I_(0) (R + R_(A))`
`(V_(0))/(I_(0)) = R + R_(A)`
`R' = R + R_(A) implies (R_(A) - R')`