LIGHT : REFLECTION AND REFRACTION 10

PRACTICE PAPER 
SUB: PHYSICS (2020)

CLASS-X               LIGHT-REFLECTION AND REFRACTION                       
                    

________________________________________________________________

I. Very Short Answer Type Questions: 

1. What do you understand by regular and defused reflection? 
2. What is lateral inversion?
3. What does m = +1 stand for?
4. What is the focal length of a plane mirror?
5. Define the refraction of light. 
6. Name the type of mirror which always forms a virtual and diminished image.
7. What Sign is given to the focal length of a concave mirror and convex mirror? 
8. In which of the following media glass water and diamond 
   (a) light travels fastest 
   (b) light travels slowest.
9. State the relation between object distance, image distance, and focal length of a spherical mirror. 
10. A 10 mm long nail is placed vertically in front of a concave mirror. A 5 mm long image of the nail is formed at 30 cm in front of the mirror. What is the focal length of this?
11. Under which conditions, a concave mirror can form an image larger than the actual object?
12. What is the minimum distance between an object and its real image in the case of the concave mirror?
13. Rays from sun converge at a point 15 cm in front of a concave mirror. Where an object should be placed so that the size of its image is equal to the size of the object?
14. In which of these media the ray of light incident obliquely at the same angle would be the most water mustard oil, glycerine, and kerosene.
15. What is the unit of the refractive index? 
16. The refractive index of diamond is 2.42. What is the meaning of this statement?
17. Why is the refractive index of the atmosphere different at different altitudes?
18. What is the difference between virtual images and real images?
19. What are the two factors on which the lateral displacement of an emergent ray from a glass lab depends?
20. What makes things visible? 
21. What kind of mirror is used in a solar furnace? Give the reason for using this mirror. 
22. What is the range of wavelengths of visible light?
23. When a light ray passes obliquely to the atmosphere in an upward direction, how does its path generally change?
24. Why are convex mirror preferred over plane mirrors as rearview mirrors?
25. What is the change in the image observed as the object is moved from Infinity towards the concave lens?
26. What the values are of the angle of incidence 'i' and the angle of reflection 'r' for a normal incidence? 
27. How does the size of the image change as the object is brought closer from infinity towards the convex lens?
28. Does the speed of light increases or decreases in a medium in comparison to its value in a vacuum?
29. Name the mirror that can give an erect and enlarged image of an object.
30. Do all Cartesian signs applicable in each case of a spherical lens as in the mirror?
31. Why does the pool or a bottom of a tank containing water appear to be raised?
32. Where the bulb is placed in torch, searchlights, and headlights of vehicles?
33. Arrange the following common substances in the increasing order of refractive indices Ice, Kerosene, Glass, Diamond, Alcohol, Water

  II. Short answer type questions: 

1. Name the following: 
   (a) a mirror which forms an erect and enlarged image.
   (b) A mirror that forms erect and the same size image.
   (c) A mirror that forms an erect and diminished image.
2. A child is standing in front of the magic mirror, she finds the image of her head bigger, the middle portion of a body of the same size and that of leg smaller. What is the order of combinations for the magic mirror from the top?
3. Why the power of accommodation of an eye decreases with age? Explain. 
4. What do you understand by rectilinear propagation of light?
5. What is the wavelength range of visible light?
6. Attempt the following conversations:
   1 nm = .........      1 Angstrom = .......
7. A man is running towards a plane mirror at a rate of 2 m/s. With what speed is the approaching his own image?
8.  A man is running away from a plane mirror at a rate of 10 m/s. With what speed is he receding from his own images?
9. Two convex lenses A and B have the same aperture with thickness  1 cm and 1.5 cm respectively.  Compare between f(A) and f(B).
10. A ray of light falls normally on the surface of a transparent glass slab. Draw a ray diagram to show its path and also mark the angle of incidence and angle of emergence.
11. When a ray of light traveling in air enters obliquely into a glass slab, it is observed that light Ray emerges parallel to the incident Ray but it is shifted sideways slightly.  Draw a ray diagram to illustrate it. 
12. Draw a ray diagram to show the path of a ray of light when it enters 
    (i) from air to water and
    (ii) from water into the air.
13. How is the refractive index of a medium related to the speed of light? Obtain an expression for the Refractive Index of a medium with respect to another in terms of speed of light in these two media?
14. The refractive index of Diamond with respect to glass is 1.6 and the absolute Refractive Index of glass is 1.5. Find out the absolute refractive index of the diamond.
15. A convex lens of focal length 20cm can produce a magnified virtual as well as a real image. Is this a correct statement? If yes where the object shall be placed in each case for obtaining the images?
16. How are the power and focal length of a lens related? You are provided with two lenses of focal length 20 cm and 40 cm respectively. Which lens will you use to obtain more convergent light?
17. Under what condition in an arrangement of two plane mirrors, incident ray and reflected ray will always be parallel to each other, whatever may be the angle of incidence. Show the same with the help of a diagram.
18. Water has a refractive index 1. 33 and alcohol have refractive index 1.36. Which of the two mediums is optically denser? Give reasons for your answer.
19. Write any three differences between a real and a virtual image.
20. You are given a concave mirror of a focal length 'f ' can form a magnified erect as well as an inverted image of an object placed in front of it "Justify this statement, stating the position of the object with respect to the mirror in each case for obtaining this images.
21. When two or more lenses are placed in contact what will be there combined power?
22.  Light enters from air into glass plates which have refractive index 1.5. Calculate the speed of light in the glass.
23. One half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Justify your answer.
24. Calculate the distance at which an object should be placed in front of a concave lens of focal length 100 cm to obtain an erect image of double its size.
25. An image 2 /3 of the size of the object is formed by a convex lens at a distance of 12 cm from it. Find the focal length of the lens.
26. Draw the diagram for the formation of image by a concave lens and the object is placed in between infinity and optical center of the lens. State the nature of the image form.
27. Represent principal focus in the concave and convex mirror using ray diagrams.
28. An object is kept at a distance of 5 cm in front of a convex mirror of focal length 10 cm. Calculate the position and the nature of the image formed.
29. A ray of light traveling in air enters obliquely into water. Does the light-ray bend towards the normal or away from the normal? Why?
30. Where an object should be placed from a converging lens of the focal length of 20 cm to obtain a real magnified image? Name the spherical mirror used as a shaving mirror. 
31. A convex lens of a focal length 10 cm is placed at a distance of 12 cm from a wall. Calculate the distance from the lens where an object can be placed so as to form its distinct real image on the wall.
32. (a) (i) State two laws of reflection.
    (ii) State four characteristics of the image 
    (b) If the speed of light in vacuum  3x10 ^ 8m/s. Find the speed of light in a medium of absolute refractive index 1.5.
33.  An object is placed at a distance of 20 cm from a convex mirror with a focal length of 15 cm. find the position and nature of the image.
34. For the same angle of incidence in media P, Q and R, the images of refraction are 45^o, 35^o and 15^o respectively. In which medium will the velocity of light be minimum? Give reasons for your answer.
35. The refractive index of dense flint glass is 1.65 and for alcohol, it is 1.36 with respect to air. Find the refractive index of dense flint glass with respect to alcohol.
36. The radius of curvature of a concave mirror is 50 cm. Where an object should be placed from the mirror so as to form its image at infinity? Justify your answer.
37. An object is placed at a distance of 20 cm. in front of a convex mirror of radius of curvature 30 cm. Find the position and nature of the image.
38. Define the absolute refractive index of a medium. Light enters from air to water having refractive index 4/3. Find the absolute refractive index of a medium if the speed of light in a vacuum is 3 x 10 ⁸  m/s.
39. What is the difference between the virtual image produced by the concave plane and convex mirrors?
40. What does the negative sign in the value of magnification produced by the mirror indicate an image?

III. Long answer type questions: 

1. The power of a combination of lenses A and B is 5D. If the focal length of lens A is 0.15 m, what are the power and focal length of lens B?
2. How can you differentiate between plane, concave, and convex mirror without touching them?
3. Draw a well-labeled ray diagram to show where the image will form when objects are kept in different places near the: 
   (a) convex mirror (b) concave mirror. 
4. A converging lens forms a real and inverted image of an object at a distance of 100 cm from it. Where an object should 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.
5. The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between length and image is 80cm, at what distance should the candle be placed from the lens? What is the nature of the image at a distance of 80 cm and the length? 
6. Draw a diagram showing the image formation by the convex mirror when an object is placed 
   (i) between pole and focus of the mirror
   (ii) between focus and center of curvature of the mirror
   (iii) at the center of curvature of the mirror
   (iv) a little beyond the center of curvature of the mirror
   (v) at infinity
7. Size of the image of an object by a mirror having a focal length of 20cm is observed to be reduced to 1/3rd to its size. At what distance does it has been placed from the mirror? What is the nature of the image and the mirror?
8. A student wants to project the image of a candle flame on a screen 
   (i) 60 cm in front of a mirror by keeping the flame at a distance of 15 cm from its pole.
   (ii). 48 cm in front of a mirror by keeping the flame at a distance of 12 centimeters from its pole
   (a) Write the type of mirror he should use. (b)Find the linear magnification of the image produced
   (c) What is the distance between the object and its image?
   (d) Draw a diagram to show the image formation in this case.
9. Draw a 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 center.
   (ii) Parallel to its principal axis.
   (iii) Passing through the center of curvature.
   (iv) Directed towards principal focus.
10. A spherical mirror makes an image of magnification -1 on a screen when the object is placed at a distance of 50 m from the mirror.
    (i) Write the type of mirror.
    (ii) Find the distance of the image from the object.
    (iii) What is the focal length of the mirror? Draw a ray diagram to show the image formation in this case. 
11. Rohit wants to have an erect image of an object using a converging mirror of focal length 40 cm.
    (i) Specify the range of distance where the object can be placed in front of the mirror. Give reasons for your answer. 
    (ii) Will the image be bigger or smaller than the object? Draw a diagram to show the image formation in this case.
12. (i) Define the term magnification. Write the formula for the magnification of the mirror explaining the symbols used in the formula.
    (ii) The magnification produced by a convex lens is -2. What is meant by this statement and also write the information regarding the image obtained from it?
13. The image of the candle flame placed at a distance of 40 centimeters from a spherical lens is found on a screen placed on the other side of the lens at a distance of 40 centimeters from the lens. Justify the types of lenses and write its focal length.
    (i)What will be the nature of the image formed if the candle? Mention the type of mirror is used as rearview mirrors.
    (ii) Shaving mirrors. List two reasons to justify your answer in each case.
14. An object of height 6 cm is placed perpendicular to the principal axis of a concave lens of focal length 5 cm. Use the lens formula to determine the position, size, and nature of the image if the distance of the object from the lens is 10 cm.
15. Draw a ray diagram to show the path of a ray of light passing obliquely from water to alcohol. The absolute refractive index of diamond is 2.42 and the absolute refractive index of glass is 1.50. Find the refractive index of diamond with respect to glass.
16. An object is kept at a distance of 18 cm 20 cm and 13 cm from a lens of power + 5D. 
    (i) In which case or cases would you get a magnified image?
    (ii) Which of the magnified image can be bought on a screen? List two widely used applications of a screen.
    (a) A concave lens made of material of refractive index n₁ is kept in a medium of refractive index n₂. A parallel beam of light is incident on the lens. Trace the path of rays of light parallels to the principal axis incident to the concave lens after reflection when: 
    (i) n₁ > n₂,  (ii) n₁ = n₂.  Give reasons for each.
    (b) A glass slab made of material of refractive index n₁ is kept in a medium of refractive index n₂. A parallel beam of light is incident on the slab. Trace the path of rays of light emerging from the glass slab. If: 
    (i) n₁ > n₂,  (ii) n₁ = n₂. (iii) n₁<n₂
17. Two lenses have power;
     (i) + 2D,
    (ii)  - 4D. What are the nature and focal length of each lens?
    (iii) An object is kept at a distance of 100 cm from the lens of power -4D. Calculate the image distance.
18. Light enters from air to a medium X. Its speed in medium X becomes 1.5 x 10 ^ 8 m/s. The speed of light in air is 3x10 ^ 8 m/s. Find the refractive index of medium X. 
    (i) A concave mirror produces three times an enlarged image of an object placed at 10 cm in front of it. Calculate the focal length of the mirror.
    (ii) Show the information of the image with the help of a ray diagram when an object is placed 6 cm from the pole of a convex mirror.
19.  A convex lens has a focal length of 15 cm. At what distance should be 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. 
20. Explain the following terms related to spherical lenses.:
    (i) Optical center
    (ii) Center of curvature
    (iii) Principal axis
    (iv) Principal axis
    (v) Principal Focus
    (vi) Aperture
    (v) Focal length.
21. A converging lens has a focal length of 12 centimeters. Calculate at what distance should be the object be placed from the lens so that it forms an image at 48 cm on the other side of the lens.
22.  At what distance from a concave lens of the focal length of 20 cm should a 6 cm tall object be placed so that it forms an image at 15 cm from the lens. Also, determine the size of the image formed.
23. A student wants to project the image of a candle flame on the walls of a school laboratory by using a lens. 
    (i) Which type of lens should be used and why? 
    (ii) At what distance in terms of a focal length F of the lens should be placed the candle flame so as to get
    (a) a magnified and
    (b) diminished image respectively on the wall. Draw a diagram of the image in each case. Can he use this mirror to project a diminished image of the candle flame on the same wall? State how if your answer is yes and why not if your answer is no.
24. Two convex lens A & B have power P₁ and P₂ respectively and P₂ is greater than P₁. Draw a ray diagram for each lens to show which one will be more converging. Give reasons for your answer.
25. A 2.0 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 10 cm. The distance of the object from the lens is 15 cm. Find the nature, position, and size of the image. Also, find its magnification.
26. (i) Define magnification. Write to it's S.I unit. 
    (ii) You are provided with two convex lenses of the focal length of 15 centimeters and 25 cm. Which of the two is of larger power? Give the reason for your answer.
27. When light enters from air to glass the angle of incidence and reflection in air and glass are 45^o and 30^o respectively. Find the refractive index of glass.
28. 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of the image and the magnification. Describe what happens as the needle is moved farther from the mirror.
29. (i) An object is placed at a distance of 60 cm from a convex mirror where the magnification produced is 1/2. Where the object should be placed to get a magnification of 1/3?
    (ii) A small electric lamp is placed at the focus of a convex lens. State the nature of the beam of light produced by the lens. Draw a diagram to show this.
30. Draw a ray diagram in each of the following cases to show the position and nature of the image formed when the object is placed:
    (i) Between pole and focus of a concave mirror
    (ii) Between focus and Center of curvature of a concave mirror
    (iii) At the center of curvature of a concave mirror
    (v) Between infinity and pole of a convex mirror
    (vi) At infinity from a convex mirror.
31. A very thin narrow beam of white light is incidence on three glass objects shown below. Comment on the nature and behavior of the emergent beam in all three cases. There is a similarity between two of the emergent beam. Identify the two. 
32. Redraw the diagrams given below in your answer book and complete the part of the ray.

                            

Chapter 1 - Chemical Reactions and  Equations	Quick View	Questions with Solutions
Chapter 2 - Acid, Bases and Salt	Quick View	Questions with Solutions
Chapter 3 - Metal and Non-metals	Quick View	Questions with Solutions
Chapter 4 - Carbon and it's compound	Quick View	Questions with Solutions
Chapter 5 - Periodic Classification of Elements	Quick View	Questions with Solutions
Chapter 6 - Life Processes	Quick View	Questions with Solutions
Chapter 7 - Control and Co-ordination	Quick View	Questions with Solutions
Chapter 8 - How do Organisms Reproduce?	Quick View	Questions with Solutions
Chapter 9 -  Health and Heredity	Quick View
Chapter 10 -  Reflection and Refraction	Quick View	Questions with Solutions
Chapter 11 -  Human Eye Colourful World	Quick View	Questions with Solutions
Chapter 12 -  Electricity	Quick View	Questions with Solutions
Chapter 13 -  Magnetic Effect of Electric Current	Quick View	Questions with Solutions
Chapter 14 -  Sources of Energy	Quick View
Chapter 15  - Our Environment	Quick View
Chapter 16 - Management of  Natural  Resources	Quick View