Physics- Light

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Physics

 

Light

 

1-Light is a form of energy due to which we are able to see the objects.

2-Light rays consist of electromagnetic waves basically which do not require any material medium (like solid, liquid or gas) for their propagation.

3-The wavelength of visible light waves is very small. Blue light has a wavelength (in vacuum) of 434 x 10- 9m = 434 nanometers (nm), while red light has a wavelength of 768 nm.

4-When light falls on the surface of an object it can either be

Absorbed:- If an object absorbs all the light falling on it , then it will appear perfectly black for example a blackboard

Transmitted: – An object is said to transmit light if it allows light to pass through itself and such objects are transparent.

Reflected:- If an object sends back light rays falling on its surface then it is said to have reflected the light

5-The process of sending back light rays which falls on the surface of an object is called REFLECTION of light

6-Laws of Reflection of light are as follows-

a-The angle of incidence is equal to the angle of reflection, and

b-The incident ray, the reflected ray and the normal to the mirror at the point of incidence all lie in the same plane.

7-Mirrors we use on our dressing tables in our home are plane mirrors.

The difference between virtual and real image are as follows

1-A real image can be caught on a screen whereas a virtual image cannot be caught on a screen.

2-A real image is formed by the actual intersection of light rays whereas a virtual image is formed by the imaginary intersection of light rays.

3-A real image is always inverted whereas a virtual image is always erect.

4-A real image can be formed in in a screen but a virtual image can be only seen in the mirror.

5-A real image is formed when the rays of light after reflection or refraction actually meet at some point whereas a virtual image is formed when the rays of light after reflection or refraction appear to meet at a point.

6-A real image is formed by only concave mirror however a virtual image can be formed by concave, convex and plane mirror also.

 

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