Light

 

Introduction

When the sun sets the objects around us  are not visible. But, when the sun rises everything around us becomes visible. It shows that for vision the presence of light is essential. It must be kept in mind that light energy makes the surrounding objects visible, but by itself it is an invisible. When light falls on objects, it is reflected from it. When the reflected light reaches our eyes, it produces sensation of vision of the objects. The sensation of vision of the objects is formed in our eyes and we see the objects. Thus, light is a form of energy which produces sensation of vision. The light travels in the form of transverse wave. In fact, the light is a form electromagnetic wave which requires no medium for their propagation.

Nature of Light : 

Light is a form of electromagnetic wave. It travels even in vacuum. Light travels in a straight line in a medium. When light travelling thought one medium falls on the surface of another medium, a part of light is reflected in second medium at the boundary leading into another medium. A part of the incident light is turned back in to the first medium  is called reflection of light. Another part of incident light is transmitted into the second medium and bends from its original path at the surface of separation is called refraction of light. The remaining part of incident light is absorbed at the surface of separation is called absorption of light

                                                               - From class 9 science book