CLASS 7 || SUBJECT - SCIENCE || CHAPTER - 15 || LIGHT ||

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Chapter 15

Light

 

1.   State the characteristics of the image formed by a plane mirror.
Ans.(i) Plane mirror forms an erect image.
(ii) It forms a virtual image.
(iii) Size of the image is same as that of the object.
(iv)Image is formed at the same distance behind the mirror as the object stands in front of it.
(v) Image formed is a laterally inverted image i.e., right hand side of the object seems to be the left hand side and vice-versa.

 

2.   What is a virtual image? Give one situation where a virtual image is formed.
Ans. The image which cannot be taken on a screen is called virtual image. When some object is placed very close to the concave mirror we don’t get any image on the white screen placed behind the mirror. Such image is called virtual image.

 

3.   State two differences between a convex and a concave lens.

 

CONVEX LENS

CONCAVE LENS

1.   Convex lens can form both real and virtual images.

Concave lens always forms a virtual image.

2.   It can form magnified image

Image is always diminished in size.



4.  Give one use each of a concave and a convex mirror.
Ans. Use of concave mirror:
Concave mirror is used by dentists to examine the teeth.
Use of convex mirror:
Convex mirror is used as side view mirror in vehicles

5.  Which type of mirror can form a real image?
Ans. Concave mirror can form a real image.

6.  Which type of lens forms always a virtual image?
Ans. Concave lens always forms a virtual image.

 

 

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