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.

AcademicPhysicsNCERTClass 8

$(a)$. A person 1 m in front of a plane mirror seems to be $\underline{2\  m}$ away from his image.

Explanation:

The image of an object formed by a plane mirror is as far from the mirror as far the object is the mirror. Here if a person is 1 m far from the mirror then his image will be formed at the distance of 1 m from the mirror. So, the distance of the object from his image =1 m+1 m=2 m.


$(b)$. If you touch your $\underline{left}$ ear with right hand in front of a plane mirror it will be seen in the mirror that your right ear is touched with $\underline{Left\ hand}$.

Explanation:

The image of an object formed by a plane mirror is inverted. Let becomes right and right becomes left in the image.


$(c)$. The size of the pupil becomes $\underline{larger}$ when you see in dim light.

Explanation:

The size of the pupil is adjusted by eye itself according to the intensity of light. The pupil of the eye gets contracted when the intensity of the light is high and gets expanded by the eye if the intensity of light is small.


$(d)$. Night birds have $\underline{lesser}$ cones than rods in their eyes.

Explanation:

The cones of the eyes are sensitive to brighter light and rods are sensitive to the dim light. A night bird has more rods than the cones in its eyes.

raja
Updated on 10-Oct-2022 13:25:15

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