video lecture for Light- Reflection and refraction Questions
Question 1: A mirage takes place due to _________.
(a) reflection
(b) refraction
(c) total internal reflection
(d) Both (b) and (c)
Answer (d)
Question 2. Raman effect is an example of _____.
(a) coherent scattering of light.
(b) incoherent scattering of light
(c) coherent interference of light
(d) incoherent interference of light
Answer (b)
Question 3. The optical phenomenon which Newton’s theory of
light failed to explain is _____.
(a) interference
(b) polarization
(c) diffraction
(d) All the above three
Answer (d)
Question 4. An observer moves towards a stationary plane mirror
at a speed of `4 ms^{−1}`. The speed of image with respect
to mirror is _________.
(a) `4 ms^{−1}` towards the mirror
(b) `8 ms^{−1}` towards the mirror
(c) `4 ms^{−1}` away from the mirror
(d) `8 ms^{−1}` away from the mirror
Answer (a)
Question 5. The process in which the electrons in the excited
atoms are released on their own from their higher
energy state to the ground state is called _____.
(a) forced emission
(b) population inversion
(c) spontaneous emission
(d) None of these
Answer (c)
Question 6. The refractive index of diamond is `2.4`. If the velocity
of light in air or vacuum is `3\times10^{8} ms^{−1}`, then the
velocity of light in diamond is ______ `\times10^{8}ms^{−1}`.
(a) `1.25`
(b) `12.5`
(c) `0.8`
(d) `125`
Answer (a)
Question 7. A convex mirror is used
(a) by a dentist
(b) for shaving
(c) as a rear view mirror in vehicles
(d) as a light reflector for obtaining a parallel beam of
light.
Answer (c)
Question 8. When an equilateral glass prism is in minimum
deviation position
(A) the refracted ray is parallel to the base of the prism.
(B) the angle of incidence is equal to the angle of emergence
(a) Only A is true
(b) Only B is true
(c) Both A and B are true
(d) Both A and B are false
Answer (c)
Question 9. The colour of a green leaf, when white light
passing through a yellow filter is incident on it, is__________.
(a) black
(b) yellow
(c) red
(d) green
Answer (d)
Question 10. Spectrometer is used to measure ________.
(a) angle of prism
(b) refractive index of material of a prism
(c) the dispersion
(d) All the above
Answer (d)
Question 11. The expression for the magnification of a spherical
mirror in terms of focal length (f) and the distance of
the object from mirror (u) is
(a) `\frac{-f}{u-f}`
(b) `\frac{f}{f-u}`
(c) `\frac{-f}{u+f}`
(d) `\frac{f}{u+f}`
Answer (d)
Question 12. According to Newton, different colours of light are
due to the difference in ______ of the corpuscles.
(a) mass
(b) nature
(c) shape
(d) size
Answer (d)
Question 13. If the speed of light in medium `– 1` and medium `– 2` are `2.5\times10^{8} ms^{−1}` and `2\times10^{8} ms^{−1}` respectively, then the refractive index of medium `– 1` with respect tomedium `– 2` is __________.
(a) `3/2.5`
(b) `2/2.5`
(c) `2.5/3`
(d) `2.5/2`
Answer (b)
Question 14. A coin is placed at the bottom of a swimming pool. To obtain a vertical shift of `20 cm` of the image of the coin, the required height of the water column is_____ (`µ_{water}=4/3`)
(a) `20 cm`
(b) `2 m`
(c) `80 m`
(d) `80 cm`
Answer (d)
Question 15. The apparent vertical shift of the image of a coin placed at the bottom of a water tank having constant depth of water is proportional to _________.
(a) `µ`
(b) `1/µ`
(c) `µ − 1`
(d) `µ + 1`
Answer (b)
Question 16. Facts about the light
(a) Light is a form of electromagnetic radiation and a non-mechanical wave.
(b) Light waves do not require a material as a medium for propagation.
(a) Only A is true.
(b) Only B is true.
(c) Both A and B are true.
(d) Both A and B are false.
Answer (c)
Question 17. Find the correct statements related to the image formed by the plane mirror form given below.
(a) The image formed is laterally inverted, virtual and erect.
(b) The size of the image is equal to the size of the object.
(c) The object distance from the plane mirror equals the image distance from the plane mirror.
(d) All the above.
Answer (d)
Question 18. When a light ray is directed towards the principal focus of a concave mirror
(a) real image is formed
(b) a dmonished image is formed
(c) inverted image is formed
(d) All the above
Answer (d)
Question 19. An object is placed in front of a spherical mirror at a distance of `20 cm` from it.A virtual image is formed at a distance of `30 cm` from it. Arrange the following steps in the proper sequence to determine the nature and focal length of the mirror
(a) Substitute the values of v and u in the mirror formula `\frac{1}{f}=\frac{1}{u}+{1}{v}`
(b) Check whether the focal length obtained is a negative or a positive integer.
(c) Decide whether the mirror is a convex or a concave mirror based on the sign of the focal length obtained.
(d) Assign proper signs to the object distance and image distance by using the sign convention.
(e) Obtain the value of focal length.
(a) d a e b c
(b) a d b e c
(c) a b d e c
(d) b d c a b
Answer (a)
Question 20. Total reflecting prisms are prism.
(a) right angled.
(b) acute angled isosceles.
(c) right angled isosceles.
(d) obtuse angled isosceles.
Answer (c)
Question 21. The final image formed by the refracting periscope is than the reflecting periscope.
(a) bright
(b) sharp
(c) dimmer
(d) Both (a) and (b)
Answer (d)
Question 22. Light is made to travel from medium `1` to medium `3` through medium `2` as shown in figure. If `µ_{1} , µ_{2}` and `µ_{3}` a are the refractive indices of first, second and third media and `i_{2} >i_{1}`, then
(a) `sin r_{1} = sin r_{2}; sin i_{1} < sin i_{2}`
(b) `1µ_{2}> 2µ_{1}; 2µ_{3} < 3µ_{2}`
(c) `1µ_{3} < 3µ_{1}`
(d) All the above.
Answer (d)
Question 23. What are the factors that determine the angle of deviation in a prism?
(a) angle of incidence
(b) wave length
(c) angle of the prism
(d) all the above
Answer (d)
Question 24. Astigmatism can be rectified by a suitable ......... lens.
(a) concave
(b) convex
(c) cylindrical
(d) None of the above
Answer (c)
Question 25. Human eye has maximum luminous efficiency to ......... light.
(a) yellow
(b) red
(c) violet
(d) green
Answer (d)
Question 26. Arrange the proper sequence of the steps to determine the refractive index of a prism by using angle of minimum deviation method.
(a) Fix a white sheet of paper on a drawing board.
(b) Draw the outer line of the prism by placing its triangular cross-section (ABC) on the paper,
(c) Draw a line which makes a certain angle with the normal. This is the incident ray.
(d) Mark a point on one of the sides and draw a normal at that point.
(e) Fix two pins P and Q on this line.
(f) Place the prism inside its outer line and observe the pins P and Q from the other side of the prism.
(g) Fix two more pins R and S on the other sides such that the images of the pins P and Q, R and S are in a straight line.
(h) Join the points R and S and the line segments PQ and RS.
(i) Remove the pins and the prism from the paper.
(j) Draw a normal XY where the line segment RS meets the side BC.
(k) Draw a graph by taking the angle of incidence and angle of deviation along the X and Y axes, respectively.
(l) Extend line segments PQ and RS and determine the angle between them. This is known as the angle of deviation.
(m) Determine refractive index as `μ=\frac{sin(A+D_{m})}{2sin(\frac{A}{2})`
(n) Repeat the experiment for different angles of incidence and in each case, determine the angle of deviation.
(o) Determine angle (A) between the refracting surfaces of the prism. (p) Determine the minimum value of angle of deviation (Dm).
(a) a b c e d f g i h j k l m o n p
(b) a b d c e f g h i j l k o n p m
(c) b a c d e j k h i j m l n o p
(d) a b d c e f g l h k m i p o j
Answer (b)
Question 27. Find out the correct option from the following.
(a) The magnification is positive for all virtual images and is negative for all real images.
(b) The magnification of concave lens and convex mirror is always positive where as the magnification of convex lens and concave mirror can be positive or negative depending on the position of the object before the lens.
(a) Only A is true.
(b) Only B is true.
(c) Both A and B are true.
(d) Both A and B are false.
Answer (c)
Question 28. Find the incorrect statements related to the rainbow
(a) The rainbow is formed in the same direction to the position of the sun.
(b) When the light rays undergo dispersion and total internal reflection the water droplets present in the atmosphere forms rainbow.
(c) A rainbow is formed in the shape of circle.
(d) When light rays undergo one internal reflection and two refractions produce primary rainbow whereas two internal reflections and two refractions produces secondary rainbow.
Answer (a)
Question 29. Choose the incorrect option from the following options:
(a) When a monochromatic light is passed through organic liquid like benzene, toluene, etc. it results in the formation of the scattered light. Which consists of wavelengths of frequencies higher and lower that of incident monochromatic light also that of the incident light.
(b) Incident scattering is a type of scattering in which the scattered light consists of frequencies other than those of the incident light.
(c) The intensity of the scattered light in a medium is inversely proportional to the fourth power of the wavelength.
(d) Rayleigh scattering is called incoherent scattering and Raman scattering is coherent scattering
Answer (d)
Question 30. A student performs an experiment to study the nature of the image formed by a convex lens. Arrange the steps in the proper sequence.
(a) Place the lens on a V-shaped stand.
(b) Place the object at `2F_{1}`.
(c) Place the object between `2F_{1}` and `F_{1}`.
(d) Determine the focal length of the lens by focusing the lens to a distant object like a tree.
(e) Adjust the position of the screen behind the lens to obtain a clear image and study the nature of the image.
(f) Mark the positions of`F_{1}`, `2F_{1}`, `F_{2}` and `2F_{2}`.
(g) Focus the lens to a distant object like a tree.
(h) Place the object just behind `2F_{1}`.
(i) Place the object at `F_{1}`.
(j) Place the object between `F_{1}` and optic centre of the lens and observe that the image formed is virtual.
(a) a f d h e g e b e c e e j
(b) b a f h e g e c j
(c) a d f g e h e b e c e i e j
(d) a d f g e h e c e b e j e
Answer (c)
Direction for questions 31 to 37:
State whether the following statements are true or
false.
Question 31. Interference takes place whenever two or more wave
motions combine in space.
False
Question 32. In the minimum deviation position of a prism, the
refracted ray is always parallel to its base.
False
Question 33. A person suffering from myopia cannot see distant
objects clearly.
True
Question 34. The focal length of a given lens depends on the
surrounding medium.
True
Question 35. Prismatic periscopes use the principle of total internal
reflection.
True
Question 36. A dentist uses a convex mirror to view the inner parts
of a patient’s mouth.
False
Question 37. The solar spectrum in general is an absorption
Spectrum.
True
Direction for questions 38 to 44:
Fill in the blanks.
Question 38. A yellow coloured dress would appear to be
_________ when viewed through a green filter.
Question 39. Due to ________ of laser, large energy can be
concentrated into an extremely small bandwidth.
Question 40. The combination of a convex lens of power
`+ 2 D` and a concave lens of power `–2 D`, acts as
a __________
Question 41. The minimum length of a plane mirror required
to view the full image of a person `6` feet tall
is ______.
Question 42. A bird is flying `12 m` above the surface of a pond.
The apparent position of the bird as viewed by a fish
1m below the surface is __________. (`aµw=3/4`)
Question 43. An object is placed on the principal axis of a concave
mirror at a distance of `60 cm`. If the focal length of
the concave mirror is `40 cm`, then the magnification
obtained is equal to __________
Question 44. The power of a biconcave lens having focal length `25
cm` is _____.
Answer
Q38. black, Q39. high monochromatic nature, Q40. glass slab, Q41. `3` feet, Q42. `15 m`. Q43. `2`, Q44. `−4D`
Direction for question 45:
Match the entries in Column A with appropriate
ones from Column B.
Answer Key
A : d, B : g, C : i, D : h, E : a, F : j, G : b, H : f, I : c,
J : e
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