"If we turn on the torch in front of the comb and a plane mirror. We can observe the path of light rays emitted by the torch. The light rays get reflected by the plane mirror. Light rays that are coming from the source, in our case it is a torch, are called Incident Rays and Light Rays which are getting reflected by the plane mirror are called Reflected Rays.
Since Light travels in a straight path, suppose we tilt the plane mirror. Reflected rays from the tilted plane mirror make a crisscross pattern on the sheet."