LAWS OF REFLECTION OF LIGHT
There are two law of reflection of light which are applicable both in the reflection of light from the plant mirrors or from spherical mirrors. These are:
1. The angle of incidence is always equal to the angle of reflection. i.e. i = r. It means that during the reflection of light if the angle of incidence is 250 then the angle of reflection will also be 250. And if the angle of incidence is 60 then the angle of reflection will also be 600.
2. The incident ray, the normal at the point of incidence of mirror and the reflected ray, all lie in the same plane.
Special Case:- As we have already discussed that during the reflection of light the angle of incidence is always equal to the angle of reflection i.e. i = r. But now a question arise in our mind that what would happen if a ray of light falls perpendicularly on the surface of mirror? The answer to this question is that the incident light which falls perpendicularly on the surface of mirror will be reflected back along the same path, because the angle of incident for such a ray of light is zero. And because i = r so the angle of reflection will also be zero.
Test Your Understanding and Answer These Questions:
- What are the values of angle of incidence and that of angle of reflection for a normal incidence?
- A ray of light is incident on a plane mirror at an angle of 25O. What is the angle of reflection?
- What happens when a ray of light falls normally on the surface of a plane mirror?
- A ray of light is incident normally on a plane mirror. What will be its (a) Angle of incidence (b) Angle of reflection?
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