rectilinear propagation of light

The property of light that states that light always travels in a straight line.

reflection of light

The bouncing back of light from the surface of an object in the same medium.

mirror

a surface that has a highly polished reflecting surface that reflects all the light that falls on it.

plane mirrors

mirrors with a flat reflecting surface

spherical mirrors

mirrors with a reflecting surface that is either curved inwards [concave mirrors] or bulged outwards [convex mirrors]

reflected ray

the ray of light that reflects after falling on the mirror

incident ray

the ray of light that falls on the mirror

reflecting surface

the shiny surface which reflects the light

angle of incidence

the angle formed between the normal and the incidental ray

angle of reflection

the angle formed between the normal and the ray of reflection

normal

it is the perpendicular drawn on the reflecting surface at the point of incidence

plane

a flat, 2 dimensional surface with no thickness

point of incidence

the point on the mirror that is struck by the incident ray

laws of reflection

* Angle of incidence = angle of reflection * Incident ray, reflected ray, and normal all lie on the same plane

regular/ specular reflection

when a parallel beam of light falls on a highly polished smooth surface such that all rays are reflected parallel to each other.

irregular/ diffused reflection

when a parallel beam of light falls on a rough surface such that the angle of incidence is different for each ray.

formation of plane mirror

one side of a thin plane glass plate is coated in a silver substance and the silvered surface is protected by an opaque covering.

real image

when rays of light are reflected in such a way that they actually meet at some point on the screen.

virtual image

when the rays of light are reflected in such a way that they appear to meet but do not actually meet on the screen

can a real image be taken on a screen?

yes it can be taken on a screen.

can a virtual image be taken on a screen?

no it cannot be taken on a screen.

is a virtual image inverted or erect?

it is always erect.

is a real image inverted or erect?

it is always inverted.

where is a real image formed?

it is formed in front of the mirror.

where is a virtual image formed?

it is formed behind the mirror.

image formed by a plane mirror

It is always erect, is formed behind the mirror, is the same size as the object, is a virtual image, the distance of the image behind the mirror is the same as the distance of the object from the mirror, and it is laterally inverted.

uses of plane mirror

used in homes, beauty parlours, and salons; used by soldiers for signalling; used by interior designers in homes to create a sense of space.

vacuum

region of space which is free of particles

speed of light in vacuum/ air

3 x 10^8

dispersion of light

Splitting of white light into VIBGYOR.

primary colours

red, green, blue

yellow

red+green

cyan

green+blue

magenta

red+blue

white

red+blue+green

how do we see colour on a colour tv?

The TV is coated with red, green, and blue phosphors arranged in dots or stripes. The presence of colours is due to the mixing and combination of these dots.

subtraction of colors

When white light falls on an object of colour (a), the object absorbs all colours except for colour (a), and it appears colour (a).

object appearing to be black

this object absorbs every color and reflects no color.

object appearing to be white

This object reflects every colour and absorbs no colour.