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Very Short Answer Type Questions
1. Give two uses of convex lens.
[CBSE 2015]
2. What is the unit of power of a lens?
[CBSE 2015]
3. What does negative magnification means?
[CBSE 2013]
4. State the sign convention used to measure distances from mirror.
[CBSE 2010]
5. State the sign convention used to measure length of image and object.
[CBSE 2012]
6. Why do we prefer a convex mirror as a rear view mirror in vehicles?
[NCERT, CBSE 2016]
7. A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or
away from the normal? Why ?
[NCERT, CBSE 2014]
8. Describe a spherical mirror.
[CBSE 2014]
9. Write two important applications of
(i) concave mirror
(ii) convex mirror
[CBSE 2011, 13]
10. What are the advantages and disadvantages of using a convex mirror for seeing traffic in the rear?
[CBSE 2015]
11. What type of lens behavior will an air bubble inside water show?
[CBSE 2012]
12. Mention two properties of a wave: one property which varies and the other which remain constant
when the wave passes from one medium to another.
[CBSE 2010]
13. A ray of light is incident on a concave mirror after passing through the centre of curvature. What is the
angle of incidence?
[CBSE 2013]
14. A lens X has a focal length of 20 cm and a lens Y has a focal length of 40 cm. Which lens would you
select to obtain a more convergent beam of light?
[CBSE 2015]
15. Write down four important characteristics of image formed by a plane mirror.
[CBSE 2014]
16. Can a plane mirror be called a spherical mirror?
[CBSE 2011]
17. Explain why we see the sign in front of the some vehicles.
[CBSE 2015]
18. How many images are formed by two parallel mirrors?
[CBSE 2015]
19. Define the term principal focus for a convex mirror.
[CBSE 2012]
20. What is the radius of curvature of a plane mirror?
[CBSE 2015]
21. What is a prism ?
[CBSE 2012, 15, 16, 17]
22. What is the focal length of a plane mirror?
[CBSE 2011]
23. A ray is incident along ACB on a spherical mirror, where C is the curvature. In which direction will the ray
be reflected?
[CBSE 2012]
24. Define the term reflection.
[CBSE 2016]
25. State the laws of reflection.
[CBSE 2016]
26. Define the terms
(i) Angle of incidence (ii) Angle of reflection (iii) Plane of incidence
[CBSE 2016]
27. The magnification produced by a plane mirror is +1. What does this mean?
[NCERT, CBSE 2011, 13]
28. The radius of curvature of a spherical mirror is 20 cm. What is its focal length?
[NCERT, CBSE 2016]
Short Answer Type Questions
1. Name the type of mirrors used in the design of solar furnaces. Explain how high temperature is achieved
by this device.
[CBSE (Al) 2016]
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2. The image of an object by a mirror is real, inverted and is of magnification -1. If the image is at distance
of 40 cm from the mirror, where is the object placed? Where would the image be if the objects is
moved 20 cm towards the mirror? State reason and also draw ray diagram for the new position of the
objects to justify your answer.
[CBSE (Al) 2016]
3. An object of height 2.5 cm is placed at a distance of 15 cm from the optical centre ‘O’ of a convex lens of
focal length 10 cm. Draw a ray diagram to find the position and size of the image formed . Mark optical
centre ‘O’, principal focus F and height of the image on the diagram
[CBSE (Al) 2016]
4. State two positions in which a concave mirror produces a magnified image of a given object. List two
differences between the two images.
[CBSE 2016]
5. Draw the following diagram, in which a ray of light is incident on a concave/convex mirror, on your
answer sheet. Show the path of this ray, after reflection, in each case.
[CBSE 2016]
6. (a) What is meant by refraction of light?
(b) If on applying Cartesian sign convention for spherical lenses the image distance obtained is negative
state the significance of negative sign.
[CBSE 2011]
7. When does Snell’s law fail ?
[CBSE 2012, 13]
8. How can you identify the three types of mirrors without touching?
[CBSE 2016]
9. (a) What happens to a ray of light when it travels from one medium to another having equal refractive
indices?
(b) State the cause of refraction of light.
[CBSE 2016]
10. For driving a car what type of mirror would you prefer to see he traffics at your back?
[CBSE 2016]
11. AB and CD, two spherical mirrors, form parts of a hollow spherical ball with its centre at O as shown in
1
the diagram. If arc AB = 2arc CD, what is the ratio of their focal lengths ? State which of the two mirrors
will always form a virtual image of an object placed infront of it and why.
[CBSE (Al) 2016]
12. If the image formed by the lens for all the positions of the objects placed infront of it is always virtual,
erect and diminished, state the type of the lens. Draw a ray diagram in support of your answer. If the
numerical value of focal length of such a lens is 20 cm, find its power in new Cartesian sign conventions.
[CBSE (F) 2016]
13. A plane as well as convex mirror produces real image, if the object is virtual. How ?
[CBSE 2015]
14. A concave mirror and a convex lens are held in water. What changes, if any, do you expect in their focal
length?
[CBSE 2014]
15. If the image formed by a convex lens is of the same size as that of the object. What is the position and
nature of the image with respect to the lens?
[CBSE 2012, 13]
16. State the laws of refraction.
[CBSE 2011, 12, 14, 15]
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17. If the image formed by a mirror for all positions of the object placed in front of it always erect and
diminished, what type of mirror is it? Draw a ray diagram to justify your answer. Where and why do we
generally use this type of mirror?
[CBSE 2014]
18. To find the image distance for varying object distances in case of a convex lens of local length 15 cm, a
student obtains on a screen a sharp image of a bright object by placing it at 20 cm distance from the
lens. After that he gradually moves the object away from the lens and each time focuses the image on
the screen.
(a) In which direction-towards or away from the lens does he move the screen to focus the object?
(b) How does the size of image change?
(c) Approximately at what distance does he obtain the image of magnification -1?
(d) How does the intensity of image change as the object moves farther away from the lens?
[CBSE (F) 2016, 17]
19. (a) What should be the position of the object, when a concave mirror is to be used
(i) as a shaving mirror, and
(ii) in torches producing parallel beam of light?
(b) A man standing in front of a mirror finds his image having a very small head and legs of normal size.
What type of mirror are used in designing such a mirror?
[CBSE 2011]
20. (a) Why does ray of light passing through the centre of curvature of a concave mirror after reflection is
reflected back along the same path?
(a) Why are convex mirror commonly used as rear- view mirrors in vehicles?
(b) A pencil partly immersed in water in a glass tumbler appears to be displaced at the interface of air
and water. Name the phenomenon of light responsible for it.
[CBSE 2011]
21. An object of height 5 cm is placed perpendicular to the principal axis of a concave lens of focal length 10
cm. If the distance of the object from the optical centre of the lens is 20 cm. Determine the position,
nature and size of the image formed using the lens formula.
[CBSE 2015]
22. For the same angle of incidence in medium P, Q and R the angle of refraction are 45, 35 and 15
respectively. In which medium , will the velocity of light be minimum? Give reason.
[CBSE 2012]
23. The nature, size and position of image of an object produced by a lens or mirror are as shown below.
Identify the lens/mirror (X) used in each case and draw the corresponding complete ray diagram.(size of
the object about half of the image)
[CBSE 2016]
24. (a) Calculate the distance at which an object should be placed in front of a convex lens of focal length 10
cm to obtain a virtual image of double its size.
(b) In the above given case, find the magnification, if image formed is real. Express it in terms of relation
between ′𝑣′ and ′𝑢′.
[CBSE 2016]
25. One half of a convex lens is covered with a black paper.
(a) Show the formation of image of an object placed at 2 F1 of such covered lens with the help of ray
diagram. Mention the position and nature of image.
OR
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.
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[NCERT, CBSE 2011, 13, 14]
(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.
[CBSE 2016]
26. Discuss the position and nature of the image formed by a concave mirror when the object is moved
from infinity towards the pole of the mirror.
[CBSE 2015]
27. Draw a ray diagram to show the path of the refracted ray in each of the following cases. A ray of light
incident on a concave lens is
(i) passing through its optical centre
(ii) parallel to its principal axis
(iii) directed towards its principal focus.
[CBSE 2014]
28. (a) Define radius of curvature and focal length of a spherical mirror and show it on a figure.
(b) Write relation between radius of curvature and focal length of a spherical mirror.
[CBSE 2015]
29. 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.
[NCERT, CBSE 2011]
30. Name the type of mirror used in the following situations
(a) Headlights of a car
(b) Side/rear-view mirror of a vehicle.
(c) Solar furnace
Support your answer with reason
[NCERT, CBSE 2013]
31. 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.
[NCERT, CBSE 2012]
32. 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.
[NCERT, CBSE 2014]
Long Answer Type Questions
1. 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 the 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.
(iii) Where will the image of this object be, if it is placed 24 cm in front of the mirror? Draw ray diagram
for this situation also to justify your answer.
Show the positions of pole, principal focus and the centre of curvature in the above ray diagrams.
[CBSE (Al) 2016]
2. (a) A divergent lens has a focal length of 20 cm. At what distance should an object of height 4 cm from
the optical centre of the lens be placed so that its image is formed 10 cm away from the lens. Find the
size of the image also
(b) Draw a ray diagram to show the formation of image in above situation.
[CBSE (Al) 2016]
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3. A converging lens forms a real and inverted image of an object at a distance of 100 cm from it. Where
should an object be placed in front of the lens, so that the size of the image is twice the size of the
object? Also, calculate the power of a lens.
[CBSE 2014]
4. (a) Explain the following terms related to spherical lenses
(i) Optical centre
(ii) Centre of curvature
(iii) Principal axis
(iv) Aperture
(v) Principal focus
(vi) Focal length
(b) A converging lens has focal length of 12 cm. Calculate at what distance should the object be placed
from the lens so that it forms an image at 48 cm on the other side of the lens.
[CBSE 2014, 16, 17]
5. (i) Define principal focus of a concave mirror.
(ii) Why do we prefer a convex mirror as a rear view mirror in vehicles?
(iii) We wish to obtain an erect image of an object using a convex lens. Draw a ray diagram to show the
image formation in this case.
[CBSE 2011]
6. (a) For what position of the object does a concave mirror form a real, inverted and diminished image of
the object ? Draw the ray diagram.
(b) An object 4 cm high is placed at a distance of 6 cm in front of a concave mirror of focal length 12
cm. Find the position of the image formed.
[CBSE 2011]
7. (a) The refractive index of diamond is 2.42. What is the meaning of this statement?
(b) Redraw the diagram given below in your answer book and complete the path of ray.
(c) What is the difference between virtual image produced by concave, plane and convex mirrors?
(d) What does the negative sign in the value of magnification produced by a mirror indicates about a
image ?
[CBSE 2012]
8. (a) Define the following terms in the context of spherical mirrors
(i) Pole
(ii) Centre of curvature
(iii) Principal axis
(iv) Principal focus
(b) Draw ray diagrams to show the principal focus of a (i) concave mirror (ii) convex mirror
(c) Consider the following diagram in which M is a mirror and P is an object and Q is its magnified
image formed the mirror
State the type of the mirror M and one characteristics property of the image Q.
[CBSE 2016]
9. State the relation between object distance, image distance and focal length of a concave or convex
mirror. A concave mirror produces two times magnified real image of an object at 10 cm from it. Find
the position of the image.
[CBSE 2016]
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10. A ray of light enters from a medium A into a slab made-up of a transparent substance B (as shown in the
figure). Refractive indices of medium A and B are 2.42 and 1.65 respectively. Complete the path of ray
of light till it emerges of the slab.
[CBSE 2012]
11. (a) Write relation between u, 𝑣, f for lenses and for mirrors where u , 𝑣, f are object distance, image
distance and focal length respectively.
(b) The magnification produced by a concave mirror is m=+4. Write the information about the image
given by this statement.
(c) Draw a ray diagram for the following and show the formation of the image in case of concave mirror
when the object is placed
(i) between the pole and focus point
(ii) at the centre of curvature
[CBSE 2016]
12. One half of a convex lens of focal length 10 cm is covered with black paper. Can such a lens produce an
image of a complete object placed at a distance of 30 cm from the lens? Draw a ray diagram to justify
your answer. A 4 cm tall object is placed perpendicular to the principal axis of a convex lens of focal
length 20 cm.. The distance of the object from the lens is 15 cm. Find the nature, position and size of
the image.
[CBSE 2015]
13. (a) Draw a ray diagram to show the formation of the image by a convex lens when an object is placed in
front of the lens between its optical centre and principal focus.
(b) In the above ray diagram mark the object-distance(u) and the image-distance (𝑣) with their proper
sign (+ve or –ve as per the new Cartesian sign convention) and state how these distances are related to
the focal length(f) of the convex lens in this case.
(c) Find the power of a convex lens which forms a real , and inverted image of magnification -1 of an
object placed at a distance of 20 cm from its optical centre.
[CBSE 2016]
14. Which lens can be used as a magnifying glass ? For which position of object does a convex lens form
(a) a virtual and erect image?
(b) a real and inverted image of same size as that of object? Draw labeled ray diagrams to show the
formation of the required image in each of the above two cases.
[CBSE 2011]
15. An object is situated at 8 cm from a convex lens of focal length 10 cm. Find the position and nature of
image. Draw ray diagram to illustrate the formation of image(not to scale).
[CBSE 2015]
16. Suppose you have three concave mirrors A, B and C of focal length 10 cm, 15 cm and 20 cm. For each
concave mirror you perform the experiment of image formation for three values of object distance of
10 cm, 20 cm and 30 cm. Giving reason answer the following
(a) For the three object distances, identify the mirror/mirrors which will form an image of magnification
-1.
(b) Out of the three mirrors identify the mirror which would be preferred to be used for shaving
purposes/makeup.
(c) For the mirror B draw ray diagram for image formation for object distances 10 cm and 20 cm.
[CBSE (F) 2016]
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17. At what distance from a concave lens of focal length 20 cm a 6 cm tall object be placed so as to obtain
its image at 15 cm from the lens? Also calculate the size of the image formed. Draw a ray diagram to
justify your answer for the above situation and label it.
[CBSE (F) 2016]
18. Name the type of mirror used in the following
(a) Solar furnace.
(b) Side/rear-view mirror of a vehicle
Draw a labelled ray diagram to show the formation of image in each of the above two cases. Which of
these mirrors could also form a magnified and virtual image of an object? Illustrate with the help of a
ray diagram.
[CBSE 2011, 15]
19. (a) Define absolute refractive index.
(b) The path of a light ray from three different medium A, B and C, for a given angle of incidence is
shown below. Study the diagrams and answer the following questions.
(i) Which of the three medium A, B or C has maximum optical density?
(ii) Through which of the three media, will the speed of light be maximum?
(iii) Will the light travelling from A to B bend towards or away from the normal?
(iv)Will the refractive index of B relative to C be more than unity or less than unity?
[CBSE 2015]
20. What is meant by power of a lens? Define its SI unit. You have two lenses A and B of focal lengths +10
cm and -10 cm, respectively. State the nature and power of each lens. Which of the two lenses will form
a virtual and magnified image of an object placed 8 cm from the lens? Draw a ray diagram to justify your
answer .
[CBSE 2015]
21. Name the two spherical mirrors. Define them. Write any three points of difference between them.
[CBSE 2016]
22. (a) Write any three differences between concave and convex mirror.
(b) Draw ray diagram to show what happens to a ray of light after reflection from a convex mirror, if it
(i) is incident parallel to principal axis.
(ii) incident at the pole.
[CBSE 2016]
23. Draw a labeled ray diagram to locate the image of an object formed by a convex lens of focal length 20
cm when the object is placed 30 cm away from the lens.
[CBSE 2016]
24. (a) A thin converging lens forms a
(i) real magnified image.
(ii) virtual magnified image of an object placed in front of it .
Write the position of the objects in each case.
(b) Draw labeled ray diagrams to show the image formation in each case.
(c) How will the following be affected on cutting this lens into two halves along the principal axis?
(i) Focal length
(ii) Intensity of the image formed by half lens.
[CBSE 2011, 15]
25. Define the following terms in relation to concave spherical mirror
(i) Radius of curvature (ii) Aperture (iii) Focal length
[CBSE 2013, 14, 15]
26. 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.
[NCERT, CBSE 2010]
27. An object size 7.0 cm is placed at 27 cm in front of 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.
[NCERT, 2013, 15]
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28. 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 convex lens if image is equal to the size of the object? Also, find the power
of the lens,
[NCERT, CBSE 2016]
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