Laws of Reflection, Definition of Law of Reflection, Three Laws of Reflection (For CBSE, ICSE, IAS, NET, NRA 2022)

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Laws of Reflection

Definition of Law of Reflection

  • Light is known to behave in a very predictable manner.
  • If a ray of light could be observed approaching and reflecting off a flat mirror, then the behavior of the light as it reflects would follow a particular law known as the law of reflection.
  • Law: ‘The principle when the light rays fall on the smooth surface, the angle of reflection is equal to the angle of incidence, also the incident ray, the reflected ray, and the normal to the surface all lie in the same plane’

Law of Reflection

Law of Reflection
  • The diagram below illustrates the law of reflection.
    • The law defines that upon reflection from a smooth surface, the angle of the reflected ray is equal to the angle of the incident ray, with respect to the normal to the surface that is to a line perpendicular to the surface at the point of contact.
    • The reflected ray is in the plane defined by the incident ray and the normal to the surface at the point of contact of the incident ray.
  • The process through which light rays falls on the surface and gets bounced back is known as reflection of light.

Three Laws of Reflection

1. The Angle between the Incident Ray and the Normal is Equal to the Angle between the Reflected Ray and the Normal

Law 1

The Angle between the Incident Ray and the Normal

As the Angle of Incidence Increases, the Angle of Reflection Also Increases and They Are Always Equal to Each Other.

2. The Incident Ray, the Normal and the Reflected Ray are All in the Same Plane the Incident Ray, the Normal and the Reflected Ray are All in the Same Plane.

Law 2

Normal and the Reflected Ray

Changing the Direction of the Incident Ray Changes the Angle of the Plane.

Incident Ray and Refracted Ray Are on Different Sides of the Normal

3. The incident ray and the reflected ray are on different sides of the normal.

Law 3

The Incident Ray and the Reflected Ray

Uses of Reflection

  • Using the law of reflection for sound and light, we can measure accurately the distances to objects.
  • Reflection is used in periscopes to view advancing enemies in the battlefield from a safe position.
  • Reflection is the reason why we see objects.
  • Reflection by a concave mirror and a convex mirror has many uses as listed above.
    • Reflection helps in medical diagnosis and optical communications.
    • Light and Sound both follow the law of reflection, both being waves.
    • Reflection is the reason why we hear the echo of sound.

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