Answer
When switch $S$ is closed, the electric potential $V_1$ across resistor 1 remains the same.
Work Step by Step
When we consider the clockwise loop through $\mathscr{E}$ and $R_1$, we can see that the potential difference across $R_1$ must be equal to $\mathscr{E}$, whether the switch is open or closed.
When switch $S$ is closed, the electric potential $V_1$ across resistor 1 remains the same.
