Rajeshwari Tuition Center

Jeemangalam,Hosur

SCIENCE
Class 10 - Science
Time Allowed: 2 hours Maximum Marks: 80

1. The image formed by a concave mirror is virtual, erect, and magnitude. The position of object is: [1]

a) between pole and focus b) between focus and centre of curvature

c) at focus d) at pole
2. In a convex spherical mirror, reflection of light takes place at: [1]

a) a bulging-out surface b) a bent-in surface

c) an uneven surface d) a flat surface

2
3. The speed of light, in a given medium, is rd of its speed in a vacuum. The absolute refractive index of the [1]
3
medium is equal to:

a) b)
3 4

2 9

c) 2

3
d) 9

4. When a ray of light from rarer to denser it will: [1]

a) Return into the same medium b) Bend away from the normal

c) Pass straight d) Bends towards the normal

5. Assertion (A): The speed of light in glass depends upon the colour of light. [1]
Reason (R): The speed of light in glass v g =
c

ng
, the refractive index of glass is different for different colours.

a) Both A and R are true and R is the correct b) Both A and R are true but R is not the
explanation of the assertion. correct explanation of A.

c) A is true but R is false. d) A is false but R is true.

6. Assertion (A): The SI unit of power of lens is dioptre. [1]
Reason (R): The power of a concave lens is positive and that of a convex lens is negative.

a) Both A and R are true and R is the correct b) Both A and R are true but R is not the
explanation of A. correct explanation of A.

c) A is true but R is false. d) A is false but R is true.

7. Assertion (A): Refractive index of glass with respect to air is different for red light and violet light. [1]
Reason (R): Refractive index of a pair of media depends on the wavelength of light used.

a) Both A and R are true and R is the correct b) Both A and R are true but R is not the
explanation of A. correct explanation of A.

c) A is true but R is false. d) A is false but R is true.

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 8. Assertion (A): For observing traffic at back, the driver mirror is a convex mirror. [1]
Reason (R): A convex mirror has a much larger field of view than a plane mirror.

a) Both A and R are true and R is the correct b) Both A and R are true but R is not the
explanation of the assertion. correct explanation of A.

c) A is true but R is false. d) A is false but R is true.

9. Assertion (A): Mirror formula can be applied to a plane mirror. [1]
Reason (R): A plane mirror is a spherical mirror of infinite focal length.

a) Both A and R are true and R is the correct b) Both A and R are true but R is not the
explanation of the assertion. correct explanation of the assertion.

c) A is false but R is true. d) A is true but R is false.

10. Magnification produced by a rearview mirror fitted in vehicles ________. [1]

a) equal to 1 b) greater than 1

c) greater than 2 d) less than 1

11. In an experiment to determine the focal length of a convex lens, a student obtained the image of a distant [1]
window on the screen. To determine the focal length of the lens, she should measure the distance between the
_____.

a) None of these b) lens and the window only

c) lens and screen only d) screen and the window only

12. When a lemon kept in water in a bowl is viewed from outside, it appears ________ than its actual size. [1]

a) Different b) Smaller

c) Larger d) Same
13. The radius of curvature of a concave mirror is 30 cm. The focal length of the mirror will be ________ cm. [1]

a) 10 b) 15

c) 20 d) 30
14. The radius of curvature of a spherical mirror is 20 cm. What is its focal length? [1]
15. Refractive index of diamond with respect to glass is 1.6 and absolute refractive index of glass is 1.5. Find out the [1]
absolute refractive index of a diamond.
16. Find the magnification of the image formed by a spherical mirror from the following data: [1]
u = -20 cm, f = -15 cm.
17. a. The figure shows a concave mirror with its pole at P, focus F and centre of curvature C. Draw ray diagram to [2]
show the formation of image of object AB.
b. State three characteristics of the image formed.

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 c. Mention one application of image formed in this case.

18. Draw ray diagrams showing the image formation by a convex mirror when an object is placed at infinity. [2]
19. A real image 2/3rd of the size of an object is formed by a convex lens when the object is at a distance of 12 cm [2]
from it. Find the focal length of the lens.
20. A concave mirror has a focal length of 20 cm. At what distance from the mirror should a 4 cm tall object be [2]
placed so that it forms an image at a distance of 30 cm from the mirror? Also calculate the size of the image
formed.
21. a. Draw a ray diagram to show the formation of image by a concave lens when an object is placed in front of it. [2]
b. In the same diagram mark the object-distance (u) and the image-distance (v) with their proper signs (+ve or -
ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f)
of the concave lens in this case.
c. Find the nature and power of a lens which forms a real and inverted image of magnification - 1 at a distance
of 40 cm from its optical centre.*
22. A convex lens can form a (i) real, inverted and magnified image as well as (ii) virtual, erect and magnified image [2]
of an object. If the focal length of the lens is 10 cm, what should be the range of the object distance in both
cases? Draw ray diagrams to justify your answer.
23. The image formed by a spherical mirror is real, inverted and is of magnification -2. If the image is at a distance [2]
of 30 cm from the mirror, where is the object placed? Find the focal length of the mirror. List two characteristics
of the image formed if the object is moved 10 cm towards the mirror.
24. How are the power and focal length of a lens related? You are provided with two lenses of focal length 20 cm [3]
and 40 cm respectively. Which lens will you use to obtain more convergent light?
25. How can you distinguish between plane mirror, convex mirror and concave mirror by merely looking at the [3]
image formed in each case?
26. A student wants to project the image of a candle flame on a screen 80 cm in front of a mirror by keeping the [3]
candle flame at a distance of 20 cm from its pole.
i. Which type of mirror should the student use?
ii. Find the magnificent of the image produced.
iii. Find the distance between the object and its image.

27. a. Define focal length of a divergent lens. [3]

b. A divergent lens of focal length 30 cm forms the image of an object of size 6 cm on the same side as the
object at a distance of 15 cm from its optical centre. Use lens formula to determine the distance of the object
from the lens and the size of the image formed.
c. Draw a ray diagram to show the formation of image in the above situation.
28. An object is kept at a distance of 18 cm, 20 cm and 30 cm, from a lens of power+5D. (i) In which case or cases [3]
would you get a magnified image? (ii) Which of the magnified image can we get on a screen? (b) List two

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 widely used applications of a convex lens.
29. A student wants to project the image of a candle flame on the walls of school laboratory by using a lens. [5]
i. Which type of lens should he use and why?
ii. At what distance in terms of focal length F of the lens should he place the candle flame, so as to get
a. a magnified and
b. a diminished image respectively, on the wall?
iii. Draw ray diagrams to show the formation of the image in each case.

30. i. Two lenses have power of [5]

a. + 2 D
b. - 4 D.
What is the nature and focal length of each lens?
ii. An object is kept at a distance of 100 cm from each of above lenses. Calculate
a. image distance and
b. magnification in each of the two cases.
31. A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the [5]
position of the candle screen and the lens as under Position of candle = 12.0 cm Position of convex lens = 50.0
cm Position of the screen = 88.0 cm
i. What is the focal length of the convex lens?
ii. Where will the image be formed if he shifts the candle towards the lens at a position of 31.0 cm?
iii. What will be the nature of the image formed if he further shifts the candle towards the lens?
iv. Draw a ray diagram to show the formation of the image in case (iii) as said above.

32. a. A 5 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The [5]
distance of the object from the lens is 30 cm. Find the position, nature and size of the image formed.
b. Draw a labelled ray diagram showing object distance, image distance and focal length in the above case.
33. An object 6 cm in size is placed at 50 cm in front of a convex lens of focal length 30 cm. At what distance from [5]
the lens should a screen be placed in order to obtain a sharp image of the object? Find the nature and size of the
image. Also draw labelled ray diagram to show the image formation in this case.
34. i. Draw a ray diagram to show the path of the reflected ray in each of the following cases: [5]
A ray of light incident on a convex mirror
1. parallel to its principal axis, and
2. is directed towards its principal focus
ii. A 1.5 cm tall candle flame is placed perpendicular to the principal axis of a concave mirror of focal length 12
cm. If the distance of the flame from the pole of the mirror is 18 cm, use mirror formula to determine the
position and size of the image formed.
35. A concave lens of focal length 60 cm is used to form an image of an object of length 9 cm kept at a distance of [5]
30 cm from it. Use lens formula to determine the nature, position and length of the image formed. Also draw
labelled ray diagram to show the image formation in the above case.

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