Place a mirror, a shiny steel plate and a sheet of paper facing a wall. Throw a beam of light from a torch on these objects one by one such that reflected light falls on the wall. It will be seen that a patch of light falls on the wall only in case of mirror and shiny steel plate but no patch of light in case of paper. This shows shiny surfaces reflect light better.

Light travels in 1 second = 3 x 10¹⁰ cm
= 3 x 10⁵ krn
Light travels in 1 rnin = 60 x 3 x 10⁵
Light travels in 8.5 rnin = 8.5 x 60 x 3 x 10⁵
= 1530 x 10⁵ km
Therefore, the distance between the sun and the earth is 1.53 x 10⁸ km.

Any smooth or polished surface which can reflect a ray of light is called a mirror. When the reflecting surface is plane, the mirror is called plane mirror while a mirror with spherical or curved reflecting surface is called spherical mirror. Further, spherical mirrors are of two types: 
(i) Concave mirrors are the mirrors whose reflecting surface is curved inwards.
(ii) Convex mirrors are the mirrors whose reflecting surface is curved outwards.

A lens is a piece of transparent material which has one or two spherical surfaces. Contrary to mirrors where the incident rays are reflected back, in case of lens the light rays pass through the spherical surface of the lens and change their path. This is also called refraction of light.

When the incident ray is striking at 90°, the angle of reflection will also be 90° as per laws of reflection. This also means that ray of light is reflected back along the same line.

In the image before a plane mirror, our right hand will appear to touch the nose. This phenomenon is called lateral inversion.

An erect and enlarged image of an object is formed only by the concave mirror or convex lens when object is inverted and placed between F and 2F

Convex lens is a lens which can converge the sun's rays to a point and burn a hole in the piece of paper

By rotating Newton's colour disc, we can demonstrate that when seven colours are mixed together, then a white colour is formed

For a single incident ray, there will be only one reflected ray that can be obtained in respect of a plane mirror

If one half of a convex lens is covered with a black paper, then yes, the convex lens will produce the complete image of the object.

Yes, in the side mirror of scooters, convex mirror is used to have a wider field of view of the traffic.

No, we cannot get a real image for any position of an object from the mirror because convex mirror always forms virtual, erect and diminished image in spite of the position of object.

In the formation of a rainbow, the raindrops suspended in the atmosphere acts as tiny prism

As we know that sunlight consists of mixture of seven colours (i.e. VIBGYOR).