Reflection and refraction of light.
Reflection of Light:
1. What is light and define the duality of light?
2. Write five characteristics of light.
3. Explain the following terms
(a) Angle of incidence (b) Angle of reflection (c) principle axis
(d) pole (e) Aperture (f) center of curvature
(g) object (h) image
4. Write the law of reflection.
5. Define the term lateral inversion.
6. Write the properties of image formed by the plane mirror?
7. Define the principle focus of concave mirror?
8. Define the principle focus of convex mirror?
9. Explain the following term
(a) focal length (b) radius of curvature (c) object distance
(d) image distance (e) real image (f) virtual image
8. What is the relation between the focal length and radius of curvature?
9. What is the relation between the focal length, image distance and object distance?
10. Write the sign convention of coordinate system.
11. Write the rule for forming image in concave mirror?
12. Write the rule for forming image in convex mirror?
13. Define the term linear magnification.
14. The magnification produced by a plane mirror is + 1. What does this mean?
Assignment X Light
15. What are your observations when you try to see the image of a large size distant object (say a distant tree) formed
by a (i) concave mirror, (ii) plane mirror, and (iii) convex mirror?
16. We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. what should be the
range of distance of the object from the mirror? What is the nature of the image? Is the image larger or smaller
than the object? Draw a ray diagram to show the image formation in this case.
17. 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 image.
18. An object 5.0 cm in length is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30
cm. find the position of the image, its nature and size.
19. 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.
20. A ray of light is passing through the centre of curvature of a concave mirror. What will be the direction of
21. From the mirror equation
show that the image in a plane mirror is as far behind the mirror as the
object is in front of it.
22. What happens when the rays of sun are focused at a point on the paper by using concave mirror?
23. Define principal focus of a convex spherical mirror. Draw a diagram too.
24. Show geometrically that for a spherical mirror R = 2f.
25. Draw a neat diagram to show image formation by a convex mirror for an extended object placed in front of it.
State the characteristics of the image.
26. An object is placed at a distance of 12 cm in front of a concave mirror. It forms a real image 4 times larger than
the object. Calculate the distance of the image from the mirror
27. An object of 5 cm is placed at a distance of 25 cm from the pole of a concave mirror of radius of curvature 30
cm. Calculate the distance and size of the image so formed. What will be the nature of the image ?
28. A convex mirror used for rear view on an automobile has radius of curvature of 3.00 m. If a bus is located at 5.0
m from the mirror, find the position, nature and size of the image.
29. An object 2.0 cm high is placed 20.0 cm in front of a concave mirror of focal length 10.0 cm. Find the distance
fro the mirror at which a screen should be placed in order to obtain a sharp image. What will be the size and
nature of the image formed?
30. An object 2 cm in size is placed 30 cm in front of a concave mirror of focal length 15 cm. At what distance from
the mirror should a screen be placed in order to obtain a sharp image? What will be the nature and the size of the
image formed? Draw a ray diagram to show the formation of the image in this case.
31. Draw ray diagrams to show the formation of images when the object is placed in front of a concave mirror:
(i) between its pole and focus point.
(ii) Between its center of curvature and focus point.
32. An object 4.0 cm in size, is placed 25.0 cm in front of a concave mirror of foal length 15.0 cm. at what distance
from the mirror should a screen be placed in order to obtain a sharp image? Find the nature and the size of the
Refraction of Light:
1. What is refraction of light?
2. State law of refraction?
3. Define refractive index? (i) Absolute refractive index (ii) Relative refractive index
4. State the Snells law?
5. Explain the following term
(a) Angle of refraction (b) Angle of deviation (c) Angle of emergence
6. Define the principle focus of convex lens and draw its diagram?
7. Define the principle focus of concave lens and draw its diagram?
8. Write the rule for forming image in convex lens?
9. Write the rule for forming image in concave lens?
10. Explain the sign convention for the spherical lens?
11. What is lens formula?
12. What is linear magnification of spherical lens?
13. Write the relation between magnification and focal length of spherical lens?
14. How the magnification is related to the image distance and object distance?
15. Define power of lens?
16. Define one diopter?
17. What is the SI unit of refractive index?
18. What is the possible value of absolute refractive index of a medium?
19. How is the refractive index of an optical medium related to the speed of light in that medium?
20. Refractive index of water with respect to air is 1.33. What is the refractive index of air with respect to water?
21. How does refractive index of one medium with respect to another depend on their absolute refractive indices.
22. In which medium light travels faster, in a denser medium or in a rarer medium?
23. If a light ray IM is incident on the surface AB as shown, identify the correct emergent ray.
24. For the same angle of incidence of 45, the refraction angle in two transparent media P and Q is 20 and 30 ,
respectively. Which medium is optically denser out of P and Q and why?
25. What is lateral displacement of a light ray passing through a glass slab?
26. Prove that the angle of incidence is equal to the angle of emergence when a ray of light passes through a glass
27. A light ray is incident normally on a glass slab. What will be the value of lateral displacement?
28. The refractive indices of four media A, B, C and D are given in the following table:
Medium A B C D
Refractive index 1.33 1.50 1.52 2.40
29. If light travels from one medium to another, in which case the change in speed will be (i) minimum, (ii)
30. A virtual image is formed by a convex lens. Where is the object placed?
31. An image of the same size of an object is formed in a convex lens. Where is the object situated and where is
the image formed?
32. An object is placed at the focus of a concave lens, where will the image be formed?
33. Onehalf 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.
34. An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray
diagram and find the position, size and the nature of the image formed.
35. A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from
the lens? Draw the ray diagram.
36. What is the difference between virtual image of an object formed by a convex lens and that formed by a
37. Light enters from air into water which has a refractive index of 1.33. Calculate the speed of light in water. The
speed of light in air is 3.0 10 m/s.
38. If the refractive index of a medium is 2 what does its means?
39. What is the relation between the refractive index and the speed of light in that medium?
40. If the refractive index of glass w.r.t water is 1.17 then find the refractive index of water w.r.t glass.
41. If n21 and n31 be the refractive indices of medium numbers 2 and 3, respectively with respect to media number
1, then what is the value of refractive index of media number 3 with respect to media number 2?
42. With respect to air the refractive indices of water and benzene are 1.33 and 1.50 respectively. Calculate the
refractive index of benzene with respect to water.
43. With respect to air the refractive index of kerosene is 1.44 and that for diamond is 2.42. calculate the
refractive index of diamond with respect to kerosene.
44. Draw ray diagrams to show image formed by a concave lens for the object placed
(a) at infinity, (b) between infinity and optical centre of lens. State characteristics of image in each case.
45. We wish to obtain a real, inverted image of the same size as that of the object by a thin convex ens of focal
length 20cm. Where should the object be placed ? Draw the ray diagram to show the image