Q. 13 :- Why does the sky appear dark instead of blue to an astronaut?    Answer:- As an astronaut moves far away from the earth atmosphere and fly at very…

Q. 12 :- Why does the Sun appear reddish early in the morning?    Answer:- As we know, the Sun light consists of seven colours. Due to the presence of molecules…

Q. 11 :-  Explain why the planets do not twinkle.   Answer:- The planets are much closer to the earth, and are thus seen as extended sources. If we consider a…

Q. 10 :- Why do stars twinkle?    Answer:- The earth atmosphere consists of layers of different gases of varying density. Since the physical conditions of the earth’s atmosphere are…

Q. 9 :- What happens to the image distance in the eye when we increase the distance of an object from the eye?    Answer:- There is no change to the…

Q. 8 :- Why is a normal eye not able to see clearly the objects placed closer than 25 cm?    Answer:- The eye lens is composed of a fibrous, jelly-like…

Q. 7 :- Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to…

Q. 6 :- The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the…

Q. 5 :- A person needs a lens of power –5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptre….

Q. 4 :- The change in focal length of an eye lens is caused by the action of the  (a) pupil. (b) retina. (c) ciliary muscles. (d) iris.   Answer:-…