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LIGHT AND REFRACTION----CRASH QUIESTIONEER SS2 2011

1.          A concave mirror produces a magnification of ½ when an object is placed at 60cm from it. Where should the object be placed so that a virtual image of double of the size is formed?

2. A lens has a power 4D. What is its focal length and nature. 

3.      A concave mirror of focal length 10cm is placed at a distance of 35cm from the wall. How far from the wall an object be placed so that the image is formed by the mirror at the wall?

4.      A concave mirror produces a magnification of ½ when an object is placed at 60cm from it. Where should the object be placed so that a virtual image of double of the size is formed?

5.      A concave mirror of focal length 10cm is placed at a distance of 15cm from the wall. How far from the wall an object be placed so that the image is formed by the mirror at the wall?  ---3

6.         Is it possible that an optical denser medium may not possess greater mass density? Give an example to show this

7.         A ray of light is incident on a plane mirror at an angle of 30o. What is the angle of light?

8.         What is lateral inversion? Explain by giving suitable example

9.         The letter F is place d in front  of the plane  mirror?(a) How would  its image look like  when seen in a mirror (b) What is name of the phenomenon involved.

10.      In what way is the word AMBULANCE painted in front of the hospital vans? Why it is painted this way?

11.      An object is placed in front of a concave mirror between its focus and center of curvature .Show with the help of a ray diagram, the position, the size and nature of the image formed?

12.      Give at least three uses of a concave mirror?

13.      What should be the position of the object when a concave mirror is to be used? (i) As a shaving mirror (ii) as a Doctor‘s mirror.

14.      What sign (+ve or –ve) has been given to the following on the basis of Cartesian sign convention? (a) Height of real image. (b) Height of a virtual Image. 

15.     The speed of light in water is 2.25 X 108 m/s...If speed of light in vacuum be 3 X 108 m/s. Calculate the refractive index of water.

16.     (i) State of laws of refraction of light?(ii) State and Explain the principle of reversibility of light.

17.      The refractive index of one type of glass with respect to air is 1.65 and that of water with respect to air is 1.33. Calculate the refractive index of water with respect to glass.

18.     The refractive index of alcohol with respect to air is 1.36 and that of carbon disulphide with respect to air is 1.63. What will be the refractive index of alcohol with respect to carbon disulphide?

19.       A coin in a glass appears to rise as the glass is slowly filled with water. Name the phenomenon responsible for this effect.

20.      Explain with the help of a diagram, why the convex lens is also called a converging lens.

21.      Draw a labelled diagram the: (i) optical center (ii) principal axis (iii) principal focus and (iv) focal length of a convex lens.

22.      Which of the two is diverging lens: convex and concave?

23.      For what position of an object, a virtual image is formed by a convex lens?

24.      What kind of lens can form:    (a)           an inverted magnified image (b) an erect magnified image   (c) an inverted diminished image (d) an erect diminished image.

25.      A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are placed in close contact with one another (i) What is the power of this combination? (ii) What is the focal length of this combination?

26.      The focal length of a concave lens is 50 cm. What is its power? Give the defect of eye for which it is used.calculate

27.      The power of a lens is 2.5 D. What is its focal length?Give the defect of eye for which it is used.calculate by formula

28.      What do you understand by the power of a lens? Define also its unit.

29.     The power of a combination of two lenses X and Y is 5 D. If the focal length of lens X be 15 cm. Calculate the focal length of lens Y.

30.     A convex lens of focal length 5 D and a concave lens of power 7.5 D are placed in contact with each other. What is the power of this combination of lenses?

31.      A convex lens of focal length 10 cm and a concave lens of focal length 20 cm are placed in close contact with each other.(a) What is power of this combination ? (b) What is the focal length of this combination?

32.      What is total internal reflection? Under what conditions does this arise?

33.      (1) State Snell’s law. (2) Why do stars twinkle on a clear night (3) Why a pencil dipped in water seems to be bent?

34.     (i) A ray of white light breaks up into its components while passing through a glass prism. Draw a ray diagram to show the path of rays (ii) Mark the least deviated colour in your figure.

35.      Why does a piece of red cloth appear red? Describe and explain the appearance of a piece of red cloth when it is illuminated by (i) white light (ii) red light (iii) blue light

36.      In the formation of spectrum of white light by a prism :-(i) Which colour are deviated paints?                                                                                            (ii) Which colour is deviated most?

37.     A beam of red light is allowed to fall in turn on (a) black cloth, (b) red cloth, (c) white cloth, and (d) blue cloth. Describe and explain the appearance in each case.

38.     A beam of sunlight falls on a mixture of blue and yellow pigments. Which colour of white light will be reflected from this mixture? Why.

39.    (i)Define the term ‘refractive Index’? (ii)State of laws of refraction of light?

40.    The speed of light in water is 2.25 X 108 m/s...If speed of light in vacuum be 3 X 108 m/s. Calculate the refractive index of water.

41.    State and Explain the principle of reversibility of light.

42.    (a) How is refractive index of an optical medium related to the speed of light in that medium ? (b) Refractive index of water with respect to air is 1.33. What is the refractive index of air with respect to water ?(c) The refractive indices of four media A, B, C and D are given in the following table :          If light travels from one medium to another, in which case the change in speed will be (i) minimum, (ii) maximum ?           

Medium

A

B

C

D

Refractive index

1.33

1.50

1.52

2.42

43.    A bottom a glass appears to rise as the glass is slowly filled with water. Explain the cause

44.    Explain with the help of a diagram, why the convex lens is also called a converging lens.

45.    Draw a labelled diagram to show the: (i) optical center (ii) principal axis (iii) principal focus and (iv) focal length of a convex lens.

46.    What do you understand by the power of a lens? Define also its unit.

47.    The power of a combination of two lenses X and Y is 5 D. If the focal length of lens X be 15 cm.find the focal length of lens Y.

48.    What is speed of light in glass of refractive index 1.5?The speed of light in vacuum is 3 X 108 ms-1  (2)

49.    The refractive Index of diamond is 2.42. What is the meaning of this statement? (1)

50.    Why do we prefer a convex mirror as a rear-view mirror in vehicles? (1)

51.    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)

52.    (a) Between the principal focus and the center of curvature.(b)At the center of curvature.(c) Beyond the center of curvature.(d) Between the pole of the mirror and its principal focus.

53.    Two thin lenses of power +3.5 D and -2.5 D  are placed in contact. Find the power  and focal length of the  lens combination.  

54.    Distinguish between a real and virtual image. (2)

55.    When does a convex lens form (i) a virtual, erect, enlarged image  (ii) real, enlarged image?(1)

56.    A concave lens has focal length of 20 cm. At what distance from the lens a 5 com tall object is placed so that it forms an image at 15 cm from the lens? Also calculate the size of the image forms. (2)

57.    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 sharp image. What will be the size and nature of the image formed

58.    Which of the two is diverging lens: convex and concave? Give their sign of focal length?

59.    For what position of an object, a virtual image is formed by a convex lens?

60.    What kind of lens can form:   (a)  an inverted magnified image (b) an erect magnified image   (c) an inverted diminished image (d) an erect diminished image.

61.     Calculate the refractive index of glass if the velocity of light in glass is 2x 108m/s. Velocity of light in vacuum is 3x108m/s.( n = 1.5 )

62.     The refractive index of water is 4/3 and for glass it is 3/2 with respect to air. What is  the refractive index of glass with respect to water? ( n = 1.125 )

63.      An object of 5cm high is held 25cm away from a converging lens of focal length 10cm.Draw the ray diagram and find the position, size, and the nature of the image formed.

64.      An object is placed at a distance of 10cm in front of a convex mirror of radius of curvature 30cm.Find the position, size, nature of the image formed

65.    A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are placed in close contact with one another.(i) What is the power of this combination?    (ii) What is the focal length of this combination?

66.    The focal length of a convex lens is 25 cm. What is its power?

67.    The power of a lens is, - 2 D. What is its focal length

68.    For magnification m=+1 for a plane mirror, what does this signify for: (a) m=1 (b)+ve sign for m

69.    Find the nature & size  of the image formed when the object is placed at a distance of 20cm from a concave mirror of focal length 10cm? (ii)

70.    Define reflection, incident light, reflected light, angle of incidence and angle of reflection

Prepared by bhatiasir For 2011 term SA2 for PCC   ***      ( Good Luck & learn Basics)                                     

 

 
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