Light- Reflection and Refraction

What is Light?

Light is a form of energy that produces in us the sensation of sight.

State the properties of light

1. Light travels in a straight line. This property of light is knwon as rectilinear propagation of light.

2. Light travels at the speed of 3×10^8 m/s in vacuum/air.

3. Light waves are electromagnetic waves and do not require a material medium for their propagation, i.e., they can travel through vacuum.

4. Light has a dual nature, that is, it shows both wave nature and particle nature, Particles of light are known as photons.

What do you mean by diffraction of light?

If an opaque object in the path of light becomes very small, light has a tendency to bend around it. This effect is known as difraction of light.

Define reflection of light

The bouncing back of light in the same medium after striking an opaque surface is known as reflection of light.

State the laws of reflection of light

1. The incident ray, reflected ray and normal at the point of incidence all lie in the same plane.

2. The angle of reflection is always equal to the angle of incidence.

State the characteristics of real image

1. Real images are formed when light rays actually meet at a point

2. Can be obtained on a screen

3. Always inverted

State the characteristics of a virtual image

1. Virtual images are formed when light rays appear to meet at a point.

2. Cannot be obtained on a screen

3. Always erect

State the characteristics of an image formed by a plane mirror

1. It is always virtual and erect

2. The size of the image is always the same as that of the object

3. It is as far behind the mirror as the object is in front of it

4. It is laterally inverted

What are spherical mirrors?

The mirrors whose reflecting surface is curved inwards or outwards are known as spherical mirrors

What is a convex mirror?

A convex mirror is a mirror whose reflecting surface is curved outwards. It is also known as a diverging mirror.

What is a concave mirror?

A concave mirror is a mirror whose reflecting surface is bulging inwards. It also known as a converging mirror

Define Pole

The centre of the reflecting surface of a spherical mirror is known as its pole. It lies on the surface of the mirror. It is usually denoted by P

Define centre of curvature

The reflecting surface of a spherical mirror forms a part of a sphere. The centre of this sphere is the centre of curvature of the spherical mirror. It is usually denoted by C. The centre of curvature lies in front of the mirror in concave mirrors and behind the mirror in convex mirrors.

Define Radius of curvature

The radius of the sphere of which the reflecting surface of a spherical mirror forms a part is known as the radius of curvature. It is usually denoted by R.