Question

Fill in the blanks in the following.

(a) A person 1 m in front of a plane mirror seems to be ______ m away from his image.

(b) 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 _________.

(c) The size of the pupil becomes ________ when you see in dim light.

(d) Night birds have _________ cones than rods in their eyes.

Answer 1

(a) A person 1 m in front of a plane mirror seems to be __2 __ m away from his image.

(Object distance and image distance are the same from a plane mirror. The image of a person 1 m in front of a mirror is 1 m back to the mirror. Hence, the image is 1 + 1 = 2 m away from the person.)

(b) If you touch your __left__ ear with your right hand in front of a plane mirror, it will be seen in the mirror that your right ear is touched with your _left hand_.

(This is because of lateral inversion of images formed in a plane mirror.)

(c) The size of the pupil becomes __large__ when you see in dim light.

(In dim light, the amount of light entering the eye is very little. To increase the amount of light, the pupil expands.)

(d) Night birds have __less__ cones than rods in their eyes.

(Night birds can see in the night, but not in the day. They have on their retina a large number of rod cells and only a few cones.)