Two mirrors meet at right angles. A ray of light is incident on one of the mirrors at an angle of $30$ degrees as shown in figure. Find the reflected angle for the reflection on the second mirror and sketch the reflected ray.

In the figure, the incident ray, the normal, and the angle of incidence (i) are shown. $i=30$.

From law of reflection $i=r$.

So, construct the reflected ray at $30$ degrees from the normal and let it fall on the other mirror.

Now draw the second normal at the point of incidence and again measure the angle of incidence, and draw the angle of reflection.

If you consider triangle AOB, one angle is $\angle AOB={90}^0$ and $\angle OAB$ is ${60}^0$

From angle sum property third angle ie $\angle ABO={180}^0-{90}^0-{60}^0={30}^0$

So, the second incident angle will be ${60}^0$.

Hence, the second reflected angle will be $60$ degrees.