LIGHT, Class X,, MCQ Part -3
MCQ'S
MCQ Questions for Class 10 Science Light Reflection and Refraction with Answers
Students can solve NCERT Class 10 Science Light Reflection and Refraction (part-2) Latest Exam Pattern Multiple Choice Questions with Answers to know their preparation level.
Question1. The focal length of a concave mirror is
(a) negative
(b) positive
(c) depends on the position of the object
(d) depends on the position of the image
Answer (a) negative
Question2. When an object moves closer to a convex lens, the image formed by it shifts
(a) away from the lens
(b) towards the lens
(c) first towards and then away from the lens
(d) first away and then towards the lens
Answer (a) away from the lens
Question3. Light from the Sun
falling on a convex lens will converge at a point called
(a) center of curvature
(b) focus
(c) radius of curvature
(d) optical center
Answer (b) focus
Question4. When an object moves
closer to a concave lens, the image formed by it shifts
(a) away from the lens on the same side of the object
(b) towards the lens
(c) away from the lens on the other side of the lens
(d) first towards and then away from the lens
Answer (b) towards the lens
Question5. A divergent lens
will produce
(a) always real image
(b) always virtual image
(c) both real and virtual image
(d) none of these
Answer (b) Always virtual image
Question6. The nature of the image
formed by a convex mirror when the object's distance from the mirror is less than
the distance between the pole and focal point (F) of the mirror would be
(a) real, inverted, and diminished in size
(b) real, inverted, and enlarged in size
(c) virtual, upright, and diminished in size
(d) virtual, upright, and enlarged in size
Answer (c) virtual, upright, and diminished in size
Question7. The nature of the
image formed by the concave mirror when the object is placed between the focus (F)
and center of curvature (C) of the mirror observed by us is
(a) real, inverted, and diminished
(c) real, inverted, and enlarged
(b) virtual, erect, and smaller in size
(d) virtual, upright, and enlarged
Answer (b) virtual, erect, and smaller in size
Question8. Two big mirrors A
and B are fitted side by side on a wall. A man is standing at such a distance
from the wall that he can see the erect image of his face in both mirrors.
When the man starts walking towards the mirrors, he finds that the size of his
face in mirror A goes on increasing but that in mirror B remains the same
(a) Mirror A is concave and mirror B is convex
(b) Mirror A is plane and mirror B is concave
(c) Mirror A is concave and mirror B is plane
(d) Mirror A is convex and mirror B is concave
Answer (c) Mirror A is concave and mirror B is plane
Question9. No matter how far
you stand from a mirror, your image appears erect. The mirror is likely to be
(a) Only plane
(b) Only concave
(c) Only convex
(d) Either plane or convex
Answer. (d) Either plane or convex.
(Both plane and convex mirror
from erect image of an object placed in front of them irrespective of the
position of the object)
Question10. Which of the
following lenses would you prefer to use while reading small letters found in a
dictionary?
(a) A convex lens of focal length 50 cm.
(b) A concave lens of focal length 50 cm.
(c) A convex lens of focal length 5 cm.
(d) A concave lens of focal length 5 cm.
Answer. (c) A convex lens of
focal length 5 cm.
(A convex lens is preferred
because it can form a magnified image. Moreover, we prefer a lens of lower focal
length f= 5cm, so that its power is large)
Question11. If a lens and a
spherical mirror both have a focal length of -15 cm, then it may be concluded that:
(a) Both are concave.
(b) The lens is concave and the mirror is convex.
(c) The lens is convex and the mirror is concave.
(d) Both are convex.
Answer (a) Both are concave.
(As per the new Cartesian sign convention focal length of a concave mirror as well as a concave lens has a negative sign)
Question12. An optical device
forms an erect image of an object placed in front of it. If the size of the
image is one-half of the object, the optical device is:
(a) Concave mirror.
(b) Convex mirror.
(c) Plane mirror.
(d) Convex lens.
Answer (b) Convex mirror.
(Out of given optical devices only a convex mirror can form an erect
and diminished image of an object placed in front of it)
Question13.A student determines the
focal length of device ‘A’ by focusing the image of a far-off object on a
screen placed on the opposite side of the object. The devices ‘A’ is:
(a) Concave lens
(b) Concave mirror
(c) Convex lens
(d) Convex mirror
Answer. (c) Convex lens
(Only a convex lens forms the real image of a far-off object on a screen placed on the other side of the lens at a distance equal to the focal length of the lens)
Qustion14. When light is incident on a glass slap the incident ray, refracted ray, and emergent ray are in three mediums A, B, and C. If n1, n2, and n3 are the refractive indices of A, B, and C respectively and the emergent ray is parallel to the incident ray. Which of the following is true?
(a) n1 < n2 < n3
(b) n1 > n2 > n3
(c) n1 < n2 = n3
(d) n1 = n3 < n2
Answer. (d) n1 = n3 < n2
( For refraction through a glass slab n1 = n3 and n2 > n1).
Question15. The image of a candle flame found by the lens is obtained on a screen placed on the other side of the lens. According to the new Cartesian sign convention, if the image is three times the size of the flame, then the lens is:
(a) Concave by magnification is + 3.
(b) Concave by magnification is -3.
(c) Convex and magnification is -3.
(d) Convex and magnification is +3.
Answer. (c) Convex and magnification is -3.
( Only a convex lens can form a real and magnified image on the other side of it. For real image magnification is negative).
Qustion16. The power of a combination of two lenses in contact is +1.0D. If the focal length of one of the lenses of the combination is +20 cm, the focal length of the other side of the lens would be:
(a) -120.0 cm
(b) +80.0 cm
(c) -25.0 cm
(d) -20.0 cm
Answer. (c) -25.0
cm
( Here P=+1.0D
f1 = +20.0cm =
+0.20cm
P1= 1/f1 =
+1/0.2 =5.0D
P2 = P-P1 =
+1.0 –(+5.0) =-4.0 D
f2
=1/P2 = -1/4.0 =- 0.25 m =-25cm)
Question17. The image of an object placed in front of a concave
mirror of a focal length of 15 cm is of the same size as the object. The distance
between the object and the images is
(a) 15 cm.
(b) 30 cm.
(c) 60 cm.
(d) zero.
Answer. (d) zero(When an object is placed at centre of curvature of a concave mirror, its real, inverted image of the same size of formed at the centre of curvature itself. Hence, the distance between the object and the image is zero)
Question18. An object of a height of 3.0 cm is placed vertically on the principle axis of the convex lens. When the object distance is -37.5 cm, an image of -2.0 cm is formed at a distance of 25.0 cm from the lens. Next, the same size is placed vertically at 25.0 cm from the lens. In this situation, the image distance v and height h of the image is according to the new Cartesian sign convention:
(a) v = + 37.5 cm, h = + 4.5 cm
(b) v = - 37.5, h = + 4.5 cm.
(c) v = + 37.5 cm, h = - 4.5 cm.
(d) v= - 37.5 cm, h = - 4.5 cm.
Answer. (b) v = - 37.5, h = + 4.5 cm
(the lens is concave because the light ray after refraction is diverging away. Moreover, an image is formed somewhere, between the object and the lens on the same side of the object. That image must be formed between O and Y)
Questio19. The relation is equal R = 2f is valid:
(a) For the concave mirror but not for the convex mirror.
(b) For convex mirrors but not for concave mirrors.
(c) Neither for the concave mirror nor for the convex mirror.
(d) for both concave and convex mirrors.
Answer. (d) for both concave and convex mirrors.
Question20. Lens has a power of positive + 4 D it is
(a) A convex lens of focal length 4 m.
(b) A concave lens of focal length 4 m.
(c) A convex lens of focal length 0.25 m
(d) A concave lens of focal length 0.25 m
Answer. (c) A convex lens of focal length 0.25 m.
Question21. An object is placed in front of a concave lens. For all positions of the object the image formed in always:
(a) Real, diminished, and inverted.
(b) Virtual, diminished, and erect.
(c) Real, enlarged, and erect.
(d) Virtual, erect, and enlarged.
Answer. (b) Virtual, diminished, and erect.
(The image formed by a concave lens is always virtual, diminished, and erect)
Question22. In which of the following is a concave mirror used?
(a) A Solar cooker.
(b) A rear-view mirror in vehicles.
(c) A safety mirror in shopping malls.
(d) in viewing full-size images of distant tall buildings.
Answer. (a) A Solar cooker.
( A concave mirror is used in a solar cooker to focus the incident and radiation on the food item to be cooked)
Question23. A ray of light starting from the air passes through medium A with a refractive index of 1.50, enters medium B with a refractive index 1.33, and finally enters medium C with a refractive index of 2.42. If this ray emerges out in the air from C, then for which of the following pairs of media is the bending of light is least?
(a) air-A
(b) A-B
(c) B-C
(d) C-air
Answer. (b) A-B
(A-B, because relative refractive index of medium B w.r.t medium A is nearest to 1)
Question24. If a lens can converge the sun rays at a point 20 cm away from its optical centre, the power of this lens is:
(a) + 2 D
(b) - 2 D
(c) + 5 D
(d) - 5 D
Answer. (c) + 5 D
(Focal length of lens, f= +20.0 cm
f= +0.20 m
Power of lens, P=1/F
P= + 1/0.2 = + 5.0 D)
Question25. The radius of curvature of a converging mirror is 30 cm. At what distance from the mirror should an object be placed to obtain a virtual image?
(a) Infinity.
(b) 30 cm.
(c) Between 15 cm and 30 cm.
(d) Between 0 cm and 15 cm.
Answer. (d) Between 0 cm and 15 cm.
(Here R=30cm.
f = R/2 =15 cm
To form a virtual image object should be placed between 0 cm to 15 cm from the converging (concave) mirror)
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