Worksheet- Light – Reflection & Refraction
1. What are the characteristics of image formed by a plane mirror?
2. Where an object should be placed in front of a concave mirror to get unit
magnification?
3. Define pole of a spherical mirror.
4. Name the type of spherical mirror used by a dentist to see the teeth of a patient clearly.
5. A beam of light parallel to the principal axis of a concave mirror converges to a point.
What is the point called? Draw a diagram to illustrate it.
6. Draw a diagram to show the transmission of light when the angle of incidence at the
surface of separation between two transparent media is zero degree.
7. What is lateral displacement?
8. Draw neat labelled diagram to show the formation of image by a concave mirror when
an object is placed at a point
1. Beyond centre of curvature
2. At centre of curvature
3. Between F and C
4. At F
5. Between F and P. Also write the characteristics of image formed in each case.
9. Draw neat labelled diagram to show the formation of image by a convex lens when an
object is placed at a point.
1. Beyond 2F
2. At 2F
3. Between F and 2F
4. At F
5. Between F and P. Also write the characteristics of image formed in each case.
10. Write the sign conventions for a spherical lens.
11. Draw a neat labeled diagram to show lateral displacement when light is passed
through a rectangular glass slab
12. An object of height 8.0 cm is placed at 50 cm in front of a concave mirror of focal
length 30 cm. At what distance from the mirror should a screen be placed in order to
obtain a sharp image? Also find the nature and size of image.
13. An object is placed at a distance of 10cm from a convex lens of focal length 15 cm.
Find the position size and nature of image formed.
14. Write any 3 uses of a concave mirror.
15. Define magnification of a mirror.
16. A rear view mirror used in a bus has a radius of curvature 3.5 m. If the driver of the
bus locates a car at 10.0m behind the bus, find the position, nature and size of the image
of the car.
17. An object 4cm high is placed at a distance of 6 cm in front of a concave mirror of
focal length 12 cm. Find the position, nature and size of the image formed.
18. How far an object should be placed from the pole of a concave mirror of focal length
20cm to form a real image whose size is 1/5 the size of the object.
19. Define power of a lens. What is its unit? Define it.
20. A concave mirror is kept in water. Will there be any change in its focal length as
compared to that in air?
20. Light enters from air into glass plate which has a refractive index of 1.5. Calculate the
speed of light in glass. (Given, speed of light in vacuum is 3 x 108ms-1
21. A convex lens has a focal length of 40 cm. Calculate its power.
NUMERICAL PROBLEMS
22. An object 50 cm tall is placed on the principal axis of a convex lens. Its 20cm tall
image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the
focal length of the lens.
23. A concave lens has focal length 20cm. At what distance from the lens a 5 cm tall
object be placed so that it forms an image at 15 cm from the lens? Also calculate the size
of the image formed.
24. An object 2.0 cm in size is placed 20.0 cm in front of a concave mirror of focal length
10.0 cm. Find the distance from 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?
25. A convex lens has a focal length of 30 cm. Calculate at what distance should the
object be placed from the lens so that it forms an image at 60 cm on the other side of the
lens. Find the magnification produced by the lens in this case.
26. The radius of curvature of a convex mirror used on a moving automobile is 2.0 m. A
truck is coming behind it at a constant distance of 3.5 m. Calculate (i) the position and (ii)
the size of the image relative to the size of the truck. What will be the nature of the
image?
27. Find the position of an object which when placed in front of a concave mirror of focal
length 20 cm produces a virtual image, which is twice the size of the object.
28. A doctor has prescribed a corrective lens of power +1.2 D. Find the focal length of
the lens to be used. Is the lens converging or diverging? What would be the defect of the
eye?
29. A small candle 2.5 cm in size is placed 27 cm in front of a concave mirror of radius of
curvature 0.36 m. At what distance from the mirror should a screen be placed in order to
receive a sharp image? Describe the nature and size of the image. If the candle is moved
closer to the mirror, how would the screen have to be moved to obtain sharp image?
30. A concave mirror of focal length 20 cm forms a real, inverted image of same size as
that of the object. Where is the object placed with respect to the mirror? Draw
a diagram to show the image formation?
