JEE Advanced 2017 · Paper 2, Physics question 9

The instantaneous voltages at three terminals marked $X$, $Y$ and $Z$ are given by

$$V_X = V_0\sin\omega t,\quad V_Y = V_0\sin\left(\omega t + \frac{2\pi}{3}\right)\ \text{and}\ V_Z = V_0\sin\left(\omega t + \frac{4\pi}{3}\right).$$

An ideal voltmeter is configured to read rms value of the potential difference between its terminals. It is connected between points $X$ and $Y$ and then between $Y$ and $Z$. The reading(s) of the voltmeter will be