CBSE Class 10 Physics Reflection and Refraction of Light Worksheet Set C

TOPIC: LIGHT- REFLECTION AND REFRACTION

♦ ANSWER THE FOLLOWING CONCEPTUAL QUESTIONS

1 What are the properties of the image formed by plane mirror?

2 One half of a convex lens is covered with a black paper.

(a) Show the formation of image of an object placed at 2F1, of such covered lens with the help of ray diagram. Mention the position and nature of image.

(b) Draw the ray diagram for same object at same position in front of the same lens, but now uncovered. Will there be any difference in the image obtained in the two cases? Give reason for your answer.

3 Draw a ray diagram to show refraction of light through a glass slab and label on it the following:

(i)Incident ray

(ii)Refracted ray

(iii)Emergent ray

(iv)Lateral shift (displacement)

4 If the image formed by mirror for all positions of the object placed in front of it is always virtual and diminished, state the type of the mirror. Draw a ray diagram in support of your answer. Where are such mirrors commonly used and why?

5 With the help of ray diagrams, show the formation of images of an object by a concave mirror. When it is placed
(i) beyond the center of curvature (ii) at the center of curvature.

6 Draw ray diagrams to show the formation of image by an object by a concave lens when the object is placed
(i) at infinity (ii) between infinity and optical Centre of the lens.

7 What is meant by the power of a lens? What is its SI unit? Name the type of lens whose power is positive. The image of an object formed by a lens is real, inverted and of the same size as the object. If the image is at a distance of 40cm from the lens, what is the nature and power of the lens? Draw ray diagram to justify your answer

8 A student has three concave mirrors A, B and C of focal lengths 20 cm, 15 cm and 10 cm respectively. For each concave mirror he performs the experiment of image formation for three values of object distance of 30 cm, 10 cm and 20 cm.

♦ Giving reason answer the following:

(a) For the three object distances, identify the mirror which will form an image equal in size to that of object. Find at least one value of object distance.

(b) Out of the three mirrors, identify the mirror which would be preferred to be used for shaving purpose.

(c) For the mirror B, draw ray diagram for image formation for any two given values of object distance.

9 Why does a light ray incident on a rectangular glass slab immersed in any medium emerge parallel to itself? Explain using a diagram.

10 Why do we prefer a convex mirror as a rear- view mirror in vehicles?

11 a) Which mirror is used by dentists?

b) What are the advantages and disadvantages of using convex mirror for seeing traffic at the rear?

12 Define the term absolute refractive index of a medium.

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

14 Name the type of mirror used in following situations

a. Headlights of the car

b. Side/rear view mirror of a vehicle

c. Solar furnace

15 A spherical mirror produces an image of magnification -1 on a screen placed at a distance of 50 cm from the mirror.

(a) Write the type of mirror.

(b) Find the distance of the image from the object.

(c) What is the focal length of the mirror?

(d) Draw the ray diagram to show the image formation in this case.

♦ ANSWER THE FOLLOWING NUMERICALS

16 The refractive index of water is 1.33 and kerosene is 1.44. Calculate refractive index of the kerosene with respect to water.

17 State the laws of refraction of light. If the speed of light in vacuum is 3X108 m/s, find the speed of light in a medium of absolute refractive index 1.5.

18 If the speed of light in water is 2.25X108 m/s and the speed in vacuum is 3X108m/s. Calculate the refractive index of water.

19 A 5 cm tall object is placed perpendicular to the principal axis of a convex lens of focallength 20 cm. The distance of the object from the lens is 30 cm. Find the:

(i) position

(ii)nature

(iii)size of the image formed.

20 A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of image and magnification. Describe what happens to the image as the
needle is moved farther from the mirror.

21 A 5cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 10 cm. The distance of the object from the lens is 15 cm. Find the nature, position and size of the image. Also find its magnification

22 (a) The refractive index of Ruby is 1.71. What is meant by this statement?

(b) The refractive index of some medium are given below:

Crown glass - 1.52
Water - 1.33
Sapphire - 1.77
In which of the medium is the speed of light

(i) maximum

(ii) minimum (iii) Calculate speed of light in sapphire.

23 It is desired to obtain an erect image of an object, using concave mirror of focal length of 12 cm.

(i) What should be the range of distance of an object placed in front of the mirror?

(ii) Will the image be smaller or larger than the object? Draw ray diagram to show the formation of image in this case,. Show the position of pole, principal focus and the Centre of curvature in the ray diagram.

24 List the new Cartesian sign convention for reflection of light by spherical mirrors. Draw a diagram and apply these conventions for calculating the focal length and nature of a spherical mirror which forms a 1/3 times magnified virtual image of an object placed 18 cm in front of it.

25 (a)An erect image 3 times the size of the object is obtained with a concave mirror of radius of curvature 36cm .What is the position of the object.

(b) When an object is placed at a distance 60 cm from convex mirror, the magnification produced is 1/2 .Where should the object be placed to get a magnification of 1/3?

26 List four characteristics of the image formed by a concave mirror of focal length 40cm when the object is placed in front of it at a distance of 20cm from its pole

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