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Fill in the following blanks with suitable words:
(a) The angle of ................ equals the angle of reflection.
(b) A person 1 m in front of a plane mirror seems to be......... m away from his image.
(c) If you touch your.........ear with right hand in front of a plane mirror, it will be seen in the mirror that your right ear is touched with..........
(d) The size of pupil becomes...........when you see in dim light.
(e) Night birds have.........cones than rods in their eyes.
(f) The image of an object persists on the retina of an eye for about.........second even after the object has disappeared.
(g) If the still pictures of a moving object are flashed on our eyes at a rate faster than..............pictures per second, the eye perceives the object as moving.
(h) In a movie, the still pictures in proper sequence are projected on the screen usually at the rate of ...........pictures per second.
Name the part of the eye:
(a) which controls the amount of light entering the eye.
(b) which converges light rays to form the image.
(c) on which image is formed.
(d) which carries the image to brain.
(e) which changes the curvature (or thickness) of eye-lens to focus objects lying at various distances.
Man A has a defect of vision due to which he cannot see the nearby objects clearly (though he can see the distant objects clearly). On the other hand, man B has a defect of vision due to which he cannot see the distant object clearly (though he can see the nearby objects clearly). The defect in man A can be corrected by using spectacles containing lenses C whereas the defect in man B can be corrected by using spectacles containing lenses D.
(a) Name the defect of vision in man (i) A, and (ii) B.
(b) What type of lenses are (i) C, and (ii) D?
A student makes a device P by using three long and narrow strips of plane mirrors inclined at 60° to one another which enables him to see beautiful patterns made by pieces of coloured glass bangles. On the other hand, another student makes a device Q by using two plane mirrors arranged parallel to each other which helps him to see a football match clearly even when some very tall persons are sitting in front of him in the ground. What are P and Q?