Light is a form of energy that travels in the form of electromagnetic waves. Optics is a branch of physics that deals with the properties and applications of light. We use a variety of optical instruments in our everyday lives. In science laboratories, microscopes are unavoidable. In the educational, scientific, and entertainment fields, telescopes, binoculars, cameras, and projectors are used. You will learn about spherical mirrors in this lesson (concave and convex). You will also learn about light's properties, such as
When light rays fall on a smooth surface(such as a mirror), they get reflected. This reflection of light rays follows certain laws. You might have studied laws of reflection in your lower classes. Let us study them in a detailed manner.
Laws of reflection:
Consider a plane mirror \(MM'\) as shown in the below diagram. Imagine a light ray \(AO\) incident on the plane mirror at \(O\). The ray \(AO\) is called incident ray. As soon as the incident ray falls on the mirror, the plane mirror reflects the light ray along \(OB\). The ray \(OB\) is called a reflected ray. Draw a line \(ON\) at \(O\) perpendicular to \(MM'\). This line \(ON\) is called normal.
Reflection of light ray
Angle of incidence(\(i\)):
The angle made by the incident ray AO with the normal is called the angle of incidence (\(i\)).
Angle of reflection(\(r\)):
The reflected ray OB makes an angle with the normal, and this is called the angle of reflection (\(r\)).
From the figure, it is very clear that the angle of incidence is equal to the angle of reflection. i.e., \(i\) \(=\) \(r\). Also, the incident ray, the reflected ray and the normal at the point of incidence all lie in the same plane.
Laws of reflection are given as:
- The incident ray, the reflected ray and the normal at the point of incidence all lie in the same plane.
- The angle of incidence is equal to the angle of reflection.