Light - Reflection and Refraction | Class 10 CBSE | Web Notes | Part 1: Introduction, Reflection of Light

Optics is the study of the behavior and properties of light.
An object reflects light that falls on it. Eyes receive the reflected light, and thus we see that object.
We see through a transparent medium as light is transmitted through it.
Light seems to travel in straight lines. A small source of light casts a sharp shadow of an opaque object. It is usually indicated as a ray of light.

If there is a very small opaque object in the path of light, it shows a tendency to bend around it. This effect is called diffraction. Here, the straight-line concept fails.
Such phenomena can be explained by considering light as a wave. But wave theory often becomes inadequate for the treatment of the interaction of light with matter, and light often behaves like a stream of particles.
Quantum theory reconciles the particle properties with the wave nature.

REFLECTION OF LIGHT

Angle of incidence is equal to the angle of reflection.
The incident ray, the normal to the mirror at the point of incidence, and the reflected ray all lie in the same plane.

These laws are applicable to all types of reflecting surfaces, including spherical surfaces.
A highly polished surface, such as a mirror, reflects most of the light falling on it.
The image formed by a plane mirror is virtual and erect. The size of the image is equal to that of the object. The image formed is as far behind the mirror as the object is in front of it. Further, the image is laterally inverted.

Consider the curved surface of a large shining spoon as a curved mirror. The image at its concave side is real, inverted, and diminished. If the spoon is moved away, the image becomes smaller.
The image at the convex side is virtual, erect, and diminished. If the spoon is moved away, the image becomes smaller.
The most commonly used type of curved mirror is the spherical mirror.

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