7. Rays and waves 7.01 light rays and waves

Rainbow

Characteristics of light Light is a form of radiation Light travels in straight lines Light transfers energy Light travels as waves Light can travel through empty space (vacuum) Speed of Light is 300 000 km/sec

Light in Everyday Life Light is a form of energy, radiative energy 1 Watt = 1 Joule/sec Light has color A prism split light into a spectrum (rainbow of colors) Light travels with a speed of c=300,000km/s

Properties of light Dispersion of light: Splitting of white light into its constituent colours

Light Travels In Straight Line Experiment Experimental setup light-travels-in-straight -line

No light is seen when one of the boards is displaced That is when the slits are not in a straight line. Conclusion : in a homogenous transparent medium, light travels in a straight line. homogenous : having the same properties throughout

We represent the path of the light by a straight line called the light ray. The arrow indicates the direction of travel of the light. Light from a point source spreads in all directions.

A light beam is a collection of light rays.

Luminous & non- luminous objects Luminous objects– Objects that emit their own light. eg- sun, lamps, lasers, glowing TV screens Non-luminous objects- Object that do not emit their own light. They reflect light. eg- moon,