Question

A voltmeter connected in series with a resistance `R_1` to a circuit indicates a voltage `V_1=198V`. When a series resistor `R_2=2R_1` is used, the voltmeter indicates as voltage `V_2=180V`. If the resistance of the voltmeter is `R_V=900Omega`, then the applied voltage across `A` and `B` is

A. `210V`
B. `200V`
C. `220V`
D. `240V`

Answer 1

Correct Answer - C
In series `PD` distribution in direct ratio of resistance
In first case
`198/(V_(AB)-198)=900/R_1` ………i
In second case `180/(V_(AB)-180)=900/(2R_1)`……….ii
Solving the two equations, we get
`V_(AB)=220V`