Reflection of Light

Reflection of Light:

When a ray of light falls on a surface it can undergo one of the following phenomena:

  • Reflection
  • Refraction
  • Absorption

Let us begin with the reflection of light. Have you ever wondered how we are able to see different objects around us? How we are able to see our image in a mirror? Well, the answer is pretty simple. Reflection of light enables us to encounter these situations. Let us see how reflection works and what the laws of reflection are? Before getting into that let us discuss few terms related to reflection.

When a ray of light strikes an opaque surface, reflection of light takes place. When reflection occurs, the direction of light ray alters. When a ray of light PO strikes the surface of a mirror, it gets reflected back in the direction as shown in fig. 1.

Reflection of light

1. Incident Ray: The ray of light PO, which strikes the surface of the mirror is known as the incident ray.

2. Reflected Ray: The ray of light which is reflected back into the original medium when the incident ray strikes the surface of the mirror is known as the reflected ray. Here, OQ is the reflected ray.

3. Normal: The line drawn perpendicular to the point of incidence O, is the normal.

4. Angle of Incidence: The angle which the incident ray makes with the normal is known as angle of incidence. \(θ_i\) represents the angle of incidence in fig. 1.

5. Angle of Reflection: The angle which the reflected ray makes with the normal is known as angle of reflection. \(θ_r\) represents the angle of reflection in fig. 1.

Laws of Reflection:

On a smooth surface, reflection of light follows the following laws:

1. The angle of incidence is equal to the angle of reflection.

\(θ_i~=~θ_r\)

Where \(θ_i\) is the angle of incidence and \(θ_r\) is the angle of reflection

2. When reflection of light occurs, the incident ray, reflected ray and normal to the reflecting surface at the point of incidence of the light ray, lie in the same plane.

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What is the nature of light?