Light And Optics - SS1 Physics Past Questions and Answers - page 3

The laws of refraction state that when light passes from one medium to another, it bends or changes direction. The first law states that the incident ray, the refracted ray, and the normal to the interface at the point of incidence all lie in the same plane. The second law, known as Snell's law, mathematically relates the angles of incidence and refraction with the refractive indices of the two media. The angle of incidence is the angle between the incident ray and the normal, and the angle of refraction is the angle between the refracted ray and the normal.

The refractive index is a measure of how much light is bent when passing through a medium. It is the ratio of the speed of light in a vacuum to the speed of light in the medium. The laws of refraction explain why light bends when it passes from air to water, glass to air, or any other two different media.

A convex lens is a lens that is thicker at the centre and thinner at the edges. When light passes through a convex lens, it converges or comes together. This convergence of light rays is due to the shape of the lens and the refractive properties of the material. The convex shape causes the light rays to bend inward towards the centre of the lens.

This bending is known as refraction. As a result, parallel rays of light that pass through a convex lens converge and meet at a point called the focal point. The distance from the centre of the lens to the focal point is called the focal length. The behaviour of light passing through a convex lens allows it to form images, and it is the basis for the functioning of optical devices such as magnifying glasses, cameras, and telescopes.