Three moving iron type voltmeters are connected as shown below. Voltmeter readings are $V$, $V1$ and $V2$ , as indicated. The correct relation among the voltmeter readings is

- $V=\dfrac{V1}{\sqrt{2}}+\dfrac{V2}{\sqrt{2}}$
- $V =V_1 +V_2$
- $V =V_1V_2$
- $V =V_2 - V_1$