Kaleidoscope is an instrument used to make numerous beautiful patterns.
To make a kaleidoscope get three rectangular mirror strips. Join them together to from a prism. Close one end of tube by cardboard disc having a hole in the centre. Paste a piece of transparent plastic sheet at the other end. Put several small pieces of coloured glass bangles. Allow enough space for the coloured pieces to move around.
Numerous beautiful patterns will be formed. It is used by designers of wall papers and fabrics and artists to get new ideas for new patterns.

In people suffering from cataract, the eye lens becomes clouded. Cataract is treated by replacing the opaque lens with a new artificial lens.

As Boojho is not in the range of reflecting surface rather, he is standing away from the mirror, so he cannot see himself in the mirror. But he can see the image of P which is in the reflecting area but not of Q and R.

Infinite number of images will be formed due to multiple reflections of light.

(a) Polished wooden table As the surface is smooth, so there is a regular reflection through it.
(b) Chalk powder Since, the surface is not smooth or it is uneven, thus there is a diffused reflection through it.
(c) Cardboard surface As its surface is uneven, so it will produce a diffused reflection.
(d) Marble floor with water spread over it As marble floor itself is very smooth, besides this there is a layer of water on it which makes the surface for regular reflection.
(e) Mirror Since, the surface of mirror is smooth, thus it will produce a regular reflection.
(f) Piece of paper Since, the surface is uneven, thus it will produce a diffused reflection.

Lack of vitamin A in food stuff is responsible for many eye troubles. Most common among them is night blindness. One should, therefore, include in the diet components which have vitamin A. Raw carrots, broccoli, green vegetables and cod liver oil are rich in vitamin A. Eggs, milk, curd, cheese, butter and fruits such as papaya and mango are also rich in vitamin A.

The two laws of reflection:
(i)The incident ray, reflected ray and normal lie in the same plane.
(ii)Angle of incidence is always equal to angle of reflection.

Iris has different colours, so the iris gives to its colour the eyes.

Our eyes are not so sensitive for a large speed and when any object is very near, the ciliary muscles cannot focus the object so early.

The ray is reflected infinite times between the two plane mirrors placed parallel to each other.

An activity to show that the incident ray, the reflected ray and the normal at the point of incidence, all lie in the same plane is as follows:
(i) Fix a white sheet of paper on a drawing board or a table.
(ii) Take a comb and drain all its openings except one in the middle using a slack paper.
(iii) Hold the comb perpendicular to the sheet of paper.
(iv) Throw light from a torch through the opening of the comb from one side.
(v) With the adjustment of the torch and comb, we see a ray of light along the paper strike the mirror.
(vi) After striking the mirror the ray of light is reflected in another direction. The ray that strikes any surface is called the incident ray.
(vii) The ray that comes back from the surface after reflection is called the reflected ray.
Theoretically, we can describe the above activity as follows:
(1) Draw a straight horizontal line with small slanted line on it showing the painted side of the mirror as shown in the figure below.
  
(2) Draw the incident ray, reflected ray and normal as shown such that the angle of incidence is equal to the angle of reflection and all the three rays lie in the same plane.

(a) While entering the cinema hall along with her friends, pupil of Pooja's eyes gets expanded due to which for few minutes she was unable to see the things around her. On the other hand, when she made on exit fromthe mall, at that moment, her pupil of her eyes becomes contracted and a large amount of light entered in her eyes due to which she felt discomfort to get things around her. But after few minutes, the pupil size starts increasing and she was able to observe the surroundings.
(b) Pooja seems to be very intelligent and conscious minded as she wore her goggle at the same time when she was feeling discomfort due to the large amount of light coming through the sun rays.

Kaleidoscope is a cylinder with mirrors containing loose, coloured objects such as beads or pebbles and bits of glass. As the viewer looks into one end, light entering the other creates a colourful pattern due to reflection. Its applications are given below:
(i) It works on the principle of multiple reflections, where several mirrors are placed at an angle (usually 60°) to one another. Typically, these are three rectangular mirrors set at 60° to each other so that they form an equilateral triangle.
(ii) The 60° angle creates seven duplicate images of the objects, 5 at 60° and 2 at 90°. As the tube is rotated, the tumbling of the coloured objects presents varying colours and patterns.
(iii) It is used in decoration purposes, toys, etc.

As per the given information point 'O' initial position of the man and I initial position of the image of the man can be show with the help of a figure.

Point O' final position of the man and I' final position of the image of the man. From the figure,
O'P + PI' = 5m [O'P = PI']
\(\Rightarrow\)   O'P+ O'P = 5m
\(\Rightarrow\)  O'P = 2.5m
Distance walked by the man = OP - O'P
 = 10 - 2.5
= 7.5m.

The correct diagrams are as below:

In a cartoon film, the movement of cartoons is completely perceived by brain after getting signals from optic nerve. Since persistence of vision is completely brain centred.
The image is formed on retina which changes continuously and through optic nerve, signals reach to the brain and brain orders eyes to watchit in continuous motion.

Laws of reflection are always followed whatever be the surface of the object.

The outer part is cornea labelled as C (this is a thin layer).