## physics - light - reflection and refraction ## Class 10 - Physics

#### Light - Reflection and Refraction

MCQ
Q&A
Question:

Define the focus of a concave mirror. If the radius of curvature of a convex mirror is 30 cm, what would be its focal length? [Foreign]

The point on the principal axis where all the rays parallel to it meet after reflection is called focus. Since, R = 30 cm and f=R/2 we have, f=+15 cm for a convex mirror. Light - Reflection and Refraction - Questions
1.

Define the principal focus of a concave mirror?

2.

List four properties of the image formed by a plane mirror. [Delhi]

3.

Draw the ray diagram in each case to show the position and nature of the image formed when the object is placed:
(i) at the centre of curvature of a concave mirror
(ii) between the pole P and focus F of a concave mirror
(iii) in front of a convex mirror
(iv) at 2F of a convex lens
(v) in front of a concave lens

4.

What is the minimum number of rays required for locating the image formed by a concave mirror for an object. Draw a ray diagram to show the formation of a virtual image by a concave mirror. [Delhi]

5.

State the type of mirror preferred as (i) rear view mirror in vehicles, (i0 shaving mirror. Justify your answer giving two reasons in each case.[Delhi] ?

6.

Draw the following diagram in your answer book and show the formation of image of the object AB with the help of suitable rays. [All India] 7.

What is the nature of the image formed by a concave mirror if the magnification produced by the mirror is +3? [Delhi]

8.

Define the focus of a concave mirror. If the radius of curvature of a convex mirror is 30 cm, what would be its focal length? [Foreign]

9.

Name the type of mirror used in the following situations.
(b) Side/rear-view mirror of a vehicle
(c) Solar furnace

10.

To construct a ray diagram, we use two light rays which are so chosen that it is easy to know their directions after reflection from the mirror. List these two rays and state the path of these rays after reflection. Use these rays to locate the image of an object placed between centre of curvature and focus of a concave mirror. [All India]

11.

One  half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.

12.

“The refractive index of diamond is 2.42”. What is the meaning of this statement in relation to speed of light? [Delhi]

13.

Define and show on a diagram, the following terms relating to a concave mirror:
(i) Aperture

14.

The refractive index of diamond is 2.42. What is the meaning of this statement?

15.

The refractive indices of four media A, B, C and D are given in the following table: If light, travels from one medium to another, in which case the change in speed will be (i) minimum, (ii) maximum? [Delhi(C)]

16.

Redraw the given diagram and show the path of the refracted ray: [All India(C)] 17.

Define ‘refractive index of a transparent medium.’ What is its unit? Which has a higher refractive index, glass or water? [Delhi]

18.

The radius of curvature of a spherical mirror is 20 cm. What is its focal length?

19.

A concave mirror produces three times magnified (enlarged) real image of object placed at 10 cm in front of it. Where is the image located?

20.

A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the lens if the image is equal to the size of the object? Also find the power of the lens.

21.

Find the focal length of a convex mirror whose radius of curvature is 32 cm.

22.

Redraw the diagram given below in your answer book and show the direction of the light ray after reflection from the mirror. [Delhi (C)] 23.

A ray of light travelling in air enters obliquely into water. Does the light ray bend towards or away from the normal ? Why? Draw a ray diagram to show the refraction of light in this situation. [Delhi]

24.

Name the mirror that can give an erect and enlarged image of an object.

25.

Distinguish between a real and a virtual image of an object. What type of image is formed (i) by a plane mirror, (ii) on a cinema screen? [Foreign]

26.

(a) With the help of a ray diagram explain why a concave lens diverges the rays of a parallel beam of light.
(b) A 2.0 cm tall object is placed perpendicular to the principal axis of a concave lens of focal length 15 cm. At what distance from the lens, should the object be placed so that it forms an image 10 cm from the lens? Also find the nature and the size of image formed. [Foreign]

27.

Explain why a ray of light passing through the centre of curvature of a concave mirror, gets reflected along the same path. [Delhi]

28.

How should a ray of light be incident on a rectangular glass slab so that it comes out from the opposite side of the slab without being displaced?  [Foreign]

29.

The refractive index of glass is 1.50 and the speed of light in air is 3 x 108 ms-1. Calculate the speed of light in glass. [Foreign]

30.

State the two laws of reflection of light. [Delhi]

31.

An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focused image can be obtained? Find the size and the nature of the image.

32.

Draw a ray diagram and also state the position, the relative size and the nature of image formed by a concave mirror when the object is placed at the centre of curvature of the mirror. [Delhi]

33.

The refractive index of water is 1.33 and the speed of light in air is 3 x 108 ms-1. Calculate the speed of light in water. [Foreign]

34.

Between which two points related to a concave mirror should an object be placed to obtain on a screen an image twice the size of the object? [All India]

35.

An object is placed between infinity and the pole of a convex mirror. Draw a ray diagram and also state the position, the relative size and the nature of the image formed. [All India]

36.

Redraw the diagram given below in your answer book and show the direction of the light ray after refraction from the lens. [Delhi, All India(C)] 37.

Redraw the diagram given below in your answer book and show the direction of the light ray after reflection from the mirror. [Delhi (C)] 38.

A ray of light enters a rectangular glass slab of refractive index 1.5. It is found that the ray emerges from the opposite face of the slab without being displaced. If its speed in air is 3 x 108 ms-1 then what is its speed in glass? [Foreign]

39.

The magnification produced by a plane mirror is +1. What does this mean?

40.

(a) “The refractive index of diamond is 2.42”. What is the meaning of this statement?
(b) Name a liquid whose mass density is less than that of water but it is optically denser than water. [Delhi]

41.

Define one dioptre of power of a lens?

42.

Which kind of mirrors are used in the headlights of a motor-car and why? [Foreign]

43.

Redraw the diagram given below in your answer book and show the direction of the light ray after refraction from the lens. [All India (C)] 44.

Between which two points of a concave mirror should an object be placed to obtain a magnification of -3? [Delhi]

45.

An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the ¡mage.

46.

A girl was playing with a thin beam of light from her laser torch by directing it from different directions on a convex lens held vertically. She was surprised to see that in a particular direction the beam of light continues to move along the same direction after passing through the lens. State the reason for this observation. [Foreign]

47.

Find the power of a concave lens of focal length 2 m.

48.

Find the focal length of a lens of power -2.0 D. What type of lens is this?