Page 144 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

to the text objects look smaller. The text will appear to spread out & be more

distant.
By observing these effects, we can determine the type of lens without touching them.

5. Write the characteristics of the image formed by spherical mirrors.
Ans: Characteristics of the image formed by spherical mirrors:
(a) Concave mirror - They always produce real & inverted image. it can be either

diminished or magnified depending on the object's distance from the mirror.
It also produces virtual & erect image when the object is too close to the mirror
The size of the image varies with the object's distance from the mirror. It can be

smaller larger or the same size as the object.
(b) Convex mirrors - The image formed by a convex mirror is always virtual, erect &
diminished, regardless of the object's distance from the mirror.

6. Mention and draw the letters of English alphabet whose images in a plane mirror are
an identical copy of themselves.

Ans: Do it yourself.
7. Explain the term lateral inversion with the help of a diagram.
Ans: Lateral Inversion-When you reach

home after school today, stand in
front of a plane mirror. Raise your

left hand and see which hand the
image raises. Your image in the
mirror will raise its right hand. Now,

raise you right hand. You will see that
it appears to be the left hand in the
mirror. This interchange of the left and right in an object and its image is called the

lateral inversion. The image formed by a plane mirror is always laterally inverted.
8. Ambika is standing in front of a plane mirror. The distance between her and the
image is 20 m. If the mirror is moved 4 m away from her, then calculate:

(a) The distance between her and the new position of the mirror.
(b) The new distance between her and the image.

Ans: Given - Distance between Ambika & her image = 20 m
Therefore, since it is a plane mirror the distance from Ambika to the mirror between
Ambika & her image.

So, distance from Ambika to the mirror = 20 m = 10 m
2

If the mirror is moved 4 m away, then the new distance from Ambika to the mirror

= 10 m + 4 m = 14 m
Now the new distance between Ambika & her image = 2 x 14 m = 28 m

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