As we know that ciliary muscles can contract and relax, it is because they can change the kness of eye lens which results in change in its focal length. So, eye lens can make image of nearby objects and also far off objects on retina.

(a) Since it is plane mirror, so the image is formed behind the mirror or there is a lateral inversion in it.

(b) Yes, Paheli can see the image of object A.
(c) Yes, Boojho can also see the image of object A.
(d) No change in the position of the image of A.

We can take care of our eyes in the following manner:
(i) If advised, use suitable spectacles.
(ii) Too little or too much light is bad for eyes. Insufficient light can cause eye strain and headache.
(iii) Too much light like that of the sun, a powerful lamp or a laser torch can injure the retina.
(iv) Wash the eyes frequently with clean water.
(v) Always read at normal distance for vision.
(vi) Never rub your eyes.

Laser light comes from a very small hole and the lens of the laser light is also very small, so the light will penetrate into one part of the eye and it can injure the retina, whereas the normal torch spreads out the light which does not cause any harm to our eyes.
So, the beam of laser light should not be used to perform an activity.

White light can be formed by mixing the primary colours red, green and blue.

Black objects appear black because they absorb all the colours, no light is reflected.

Tap water reflects the light into our eyes. As long as an object reflects light into our eyes, we can see it.

Image stays on retina for about 1/16th of a second.

Since eyelid is also known as eye-shutter. So, it prevents any object entering the eye.

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.

(a) Number of mirrors = 3
(b) Positions of the mirrors are as shown in figure.
(c) Mirrors should be placed at 45° w.r.t. the incident light. So, that ray can move forward.
(d) Direction of rays is shown in figure.
(e) He will not be able to see the objects if any of the mirrors is removed since he will not get the rays after that removed mirror.