GATE EC 2016 Set 2 Q40 — Electronic Devices

In the opamp circuit shown, the Zener diodes $Z1$ and $Z2$ clamp the output voltage $V_{0}$ to $+5V$ or $-5 V$. The switch $S$ is initially closed and is opened at time $t=0$.

The time $t=t_{1}$ (in seconds) at which $V_{0}$ changes state is ________