Study Materials

# NCERT Solutions for Class 7th Science

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## Chapter 15. Light

Ques: What is concave mirror?
Ans: If the reflecting surface of a spherical mirror is concave, it is called a concave mirror.

Ques: What is convex mirror?
Ans: If the reflecting surface is convex, then it is a convex mirror.

Ques: What is real image?
Ans: An image formed on a screen is called a real image.

Ques: What is virtual image?
Ans: The image formed by a plane mirror could not be obtained on a screen. Such an image is called a virtual image.

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

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

Ques: Give one use each of a concave and a convex mirror.
Ans:

Use of Concave Mirror-

Use of Comcave Mirror-

(i) It is used in vehicles as side mirror.

Ques: What is convex lens?
Ans: Those lenses which feel thicker in the middle than at the edges are convex lenses.
Ques: What is concave lens?
Ans: Those which feel thinner in the middle than at the edges are concave lenses.

Ques: Why is convex lens called converging lens?
Ans: A convex lens converges (bends inward) the light generally falling on it. Therefore, it is called a converging lens.
Ques: Why is concave lens called diverging lens?
Ans: A concave lens diverges (bends outward) the light and is called a diverging lens.

Ques: Which lens is used as magnificent lens?

Ans: convex lens.

Ques: What is white light?
Ans: The sunlight consists of seven colours. The sunlight is said to be white light.
Ques: Name all colours presence in rainbow in their real order.
Or
Ques: Name all colours consist in white light.

Ans: red, orange, yellow, green, blue, indigo and violet.
Ques: How many colours are there in white light.
Ans: seven.

Ques: Fill in the blanks:

(i) An image that cannot be obtained on a screen is called _________.

(ii) Image formed by a convex __________ is always virtual and smaller in size.

(iii) An image formed by a __________ mirror is always of the same size as that of the object.

(iv) An image which can be obtained on a screen is called a _________ image.

(v) An image formed by a concave ___________ cannot be obtained on a screen.

(i) Vertual image

(ii)  miror

(iii) plane

(iv) real

(v) lens

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