Q 9.31 Light incident normally on a plane mirror attached to a galvanometer coil retraces backwards as shown in Fig. 9.33. A current in the coil produces a deflection of 3.5 degrees of the mirror. What is the displacement of the reflected spot of light on a screen placed 1.5 m away?
Given
Angle of deflection
The distance of the screen from the mirror
The reflected rays will be deflected by twice the angle of deviation which is
Now from the figure, it can be seen that.
Hence displacement of the reflected spot of the light is .