In the adjoining circuit diagram, the readings of ammeter and voltmeter are 2 A and 120 V, respectively. If the value of R is `75Omega`, then the voltmeter resistance will be

Options

A. `100Omega`
B. `150Omega`
C. `300 Omega`
D. `75 Omega`

Answer

C

Explanation

`therefore V_(AB) = (I-I_(g))R=I_(g).G`

Where, G=voltmeter(resistance).
Given, `V_(AB) = 120 V, I=2A, R=75Omega`
`rArr 120 = (2-I_(g))75 rArr I_(g) = 0.4A`
Now, `V_(AB) = I_(g)G rArr G=120/0.4 = 300 Omega`