Laws of Reflection and Image in Plane Mirror

Question 1

What is reflection?

Answer 1

The return of light into the same medium after striking a surface is called reflection.

Question 2

What are the two types of reflection? Define them.

Answer 2

(i) Regular reflection: Regular reflection occurs when a beam of light falls on a smooth and polished surface such as a plane mirror
(ii) Irregular reflection: Irregular reflection occurs when a beam of light falls on a rough surface such as the wall of a room or the page of a book

Question 3

Define:
1. Incident ray
2. Point of incidence
3. Angle of incidence
4. Plane of incidence

Answer 3

1. The light ray striking a reflecting surface is called the incident ray.
2. The point at which the incident ray strikes the reflecting surface, is called the point of incidence.
3. The angle which the incident ray makes with the normal at the point of incidence, is called the angle of incidence. It is denoted by the letter i.
4. The plane containing the incident ray and the normal, is called the plane of incidence.

Question 4

Define:
1. Reflected ray
2. Normal
3. Angle of reflection
4. Plane of reflection

Answer 4

1. The light ray obtained after reflection from the surface, in the same medium in which the incident ray is traveling, is called the reflected ray.
2. The perpendicular drawn to the surface at the point of incidence, is called the normal.
3. The angle which the reflected ray makes with the normal at the point of incidence, is called the angle of reflection. It is denoted by the letter r.
4. The plane containing the reflected ray and the normal, is called the plane of reflection.

Question 5

State the laws of reflection.

Answer 5

1. The angle of incidence i is equal to the angle of reflection r (i.e. ∠i = ∠r).
2. The incident ray, the reflected ray, and the normal at the point of incidence, lie in the same plane.