Vardaan Learning Institute

Topic: Light - Reflection and Refraction

Class: 10 (Science) Type: Bonus Practice Paper Max. Marks: 50
Name:
Date:
SECTION A: OBJECTIVE TYPE QUESTIONS (1 Mark Each)
1. The angle of reflection is equal to the angle of incidence:
  1. Always
  2. Sometimes
  3. Under special conditions
  4. Never
2. The image formed by a concave mirror is observed to be VIRTUAL, ERECT and LARGER than the object. Where should be the position of the object?
  1. Between principal focus and center of curvature
  2. At the center of curvature
  3. Beyond the center of curvature
  4. Between the pole of the mirror and its principal focus
3. Which one of the following materials cannot be used to make a lens?
  1. Water
  2. Glass
  3. Plastic
  4. Clay
4. The S.I unit of power of a lens is:
  1. Meter
  2. Watt
  3. Dioptre
  4. Centimeter
5. Where should an object be placed in front of a convex lens to get a real image of the size of the object?
  1. At the principal focus F
  2. At twice the focal length (2F)
  3. At Infinity
  4. Between optical center and F
6. The focal length of a plane mirror is:
  1. Positive
  2. Negative
  3. Zero
  4. Infinity
7. The magnification produced by a plane mirror is:
  1. -1
  2. 0
  3. +1
  4. Infinity
8. A full length image of a distant tall building can definitely be seen by using:
  1. A concave mirror
  2. A convex mirror
  3. A plane mirror
  4. Both concave as well as plane mirror
9. Which of the following lens would you prefer to use while reading small letters found in a dictionary?
  1. A convex lens of focal length 50 cm
  2. A concave lens of focal length 50 cm
  3. A convex lens of focal length 5 cm
  4. A concave lens of focal length 5 cm
10. Light travels fastest in:
  1. Water
  2. Glass
  3. Diamond
  4. Vacuum
Directions (Q11-Q14): In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false but R is true.
11. Assertion (A): The mirrors used in searchlights are concave spherical.
Reason (R): In concave mirrors, the reflected rays converge at the focus, so if source is at focus, beam becomes parallel.
12. Assertion (A): A ray of light passing through the optical center of a lens suffers no deviation.
Reason (R): The optical center is a point on the principal axis of a lens.
13. Assertion (A): The refractive index of diamond is 2.42.
Reason (R): The refractive index of a medium is the ratio of speed of light in vacuum to speed of light in that medium.
14. Assertion (A): A pencil partly immersed in water appears to be bent at the water surface.
Reason (R): This is due to the phenomenon of refraction of light.
SECTION B: SHORT ANSWER QUESTIONS (3 Marks Each)
15. Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is $3 \times 10^8$ m/s.
16. 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, nature and size of the image.
17. Draw a ray diagram to show the formation of an image by a concave mirror when the object is placed between C and F.
18. Explain the Laws of Refraction of light with the help of a diagram.
19. Why does a swimming pool appear to be shallower than it actually is? Illustrate with a ray diagram.
20. Under what conditions does a ray of light pass without deviation through: (i) a glass slab, (ii) a lens?
SECTION C: LONG ANSWER QUESTIONS (5 Marks Each)
21. (i) An object is placed at a distance of 10 cm from a convex lens of focal length 15 cm. Find the position and nature of the image.
(ii) A concave lens has focal length of 15 cm. At what distance should the object from the lens be placed so that it forms an image at 10 cm from the lens? Also, find the magnification produced by the lens.
22. (i) What is meant by power of a lens? Define 1 Dioptre.
(ii) Two thin lenses of power +3.5D and -2.5D are placed in contact. Find the power and focal length of the lens combination.
SECTION D: CASE STUDY (4 Marks)
23. Read the following text and answer the questions:
Spherical mirrors are of two types - convex and concave. Convex mirrors are used as rear-view mirrors in vehicles because they always give an erect image and have a wider field of view. Concave mirrors are converging mirrors used by dentists.

(i) Why do we prefer a convex mirror as a rear-view mirror in vehicles? (1 Mark)
(ii) A student wants to project a full length image of a tall building on a small screen. Which mirror should he use? (1 Mark)
(iii) If the radius of curvature of a spherical mirror is 20 cm, what is its focal length? (2 Marks)
24. Read the following text and answer the questions:
A convex lens forms a real and inverted image of an object. The size of the image depends on the position of the object. Lenses are used in cameras, microscopes, telescopes, and spectacles. Light refracts when passing through a lens.

(i) If an object is placed at the focus of a convex lens, where is the image formed? (1 Mark)
(ii) Which lens is used to correct hypermetropia (long-sightedness)? (1 Mark)
(iii) Calculate the power of a convex lens of focal length 25 cm. (2 Marks)
"All the best!"