STD X – LIGHT – NEWTON

REFRACTION OF LIGHT THROUGH PLANE SURFACES

As you already know, light travels along a straight line path in a single medium. It also travels in a straight path when there are two different mediums but with the same density.
Are you curious to know, the behaviour of light when it travels from one medium to another medium but with different densities?

The light ray bends at the border between the two mediums with different densities. This phenomenon is known as the refraction of light. This topic is all about refraction, laws of refraction, refractive index and all important terms related to these concepts. Refraction happens due to the varying speed of light in different media.

Refraction of light through a PRISM

The visible light or the white light which when passes through a prism is segregated into its constituent colours namely violet, indigo, blue, green, yellow, orange, and red. This phenomenon is known as the dispersion of light. This dispersion occurs due to the varying refraction angles of lights of different colours when passed through a transparent medium. Red colour refracts the least while violet colour refracts the most.

In this topic, you will learn more about refraction through the prism with the help of a diagram and also the concept of angle of deviation.

REFRACTION THROUGH A LENS

Optics is the branch of physics that deals with the properties and behavior of light. Refraction of light is the bending of light when it travels from one transparent medium to the other. Light travels at a different speed in different optical media. Refractive index is the refracting ability of a medium. Higher the refractive index denser the medium. In this topic, you will be studying about the lens as the refracting medium, important terms related to a lens, type of lens and difference between the types of lens.

Power, Magnification and Determination of Focal Length of A Lens

The capacity of a lens to bend light defines the lens power. The refraction of light is increased with the increase in lens power. Dioptres is the unit to measure lens power.

The ratio of the height of an image to the height of an object is known as the magnification of a lens. It can also be defined with respect to image distance and object distance.

The point on which all parallel rays of light converge is the focal point of a convex lens.The distance between the centre of a convex lens and the focal point of a lens is the focal length.The focal length of a convex lens can be determined by the distant object method.

SPECTRUM

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When a light ray enters one refracting surface of the prism, it bends towards the normal and when it emerges out of the other refracting surface it bends away from the normal. The angle between the incident ray and the emergent ray is the angle of deviation.

Dispersion:

The phenomenon due to which a polychromatic light, like sunlight, splits into its component colours, when passed through a transparent medium like a glass prism, is called dispersion of light.

Spectrum:

The band of colours obtained on the screen, when a polychromatic light splits into component colours is called a spectrum.