Ray Optics and Optical Instruments Practice Questions - DPP for JEE

 Page 1


PART-I (Single Correct MCQs)
1. A car is fitted with a convex side-view mirror of focal length 20 cm. A
second car 2.8 m behind the first car is overtaking the first car at a
relative speed of 15 m/s. The speed (in m/s) of the image of the second
car as seen in the mirror of the first one is :
(a) m/s
(b) 10 m/s
(c) 15 m/s
(d) m/s
2. If the refractive index of the material of a prism is  and the angle
of prism is A, then angle of minimum deviation is
(a) p – 2A
Page 2


PART-I (Single Correct MCQs)
1. A car is fitted with a convex side-view mirror of focal length 20 cm. A
second car 2.8 m behind the first car is overtaking the first car at a
relative speed of 15 m/s. The speed (in m/s) of the image of the second
car as seen in the mirror of the first one is :
(a) m/s
(b) 10 m/s
(c) 15 m/s
(d) m/s
2. If the refractive index of the material of a prism is  and the angle
of prism is A, then angle of minimum deviation is
(a) p – 2A
(b) p – A
(c)
(d)
3. A telescope has an objective of focal length 100 cm and an eyepiece of
focal length 5 cm. What is the magnifying power of the telescope when
the final image is formed at the least distance of distinct vision ?
(a) 20
(b) 24
(c) 28
(d) 3 2
4. In the figure shown, L is a converging lens of focal length 10 cm and M
is a concave mirror of radius of curvature 20cm. A point object O is
placed in front of the lens at a distance 15 cm. AB and CD are optical
axes of the lens and mirror respectively. The distance of the final image
formed by this system from the optical centre of the lens is cm.
Find the value of x in cm.
[The distance between CD and AB is 1 cm]
(a) 2
(b) 3
(c) 6
(d) 4
5. An object at 2.4 m in front of a lens forms a sharp image on a film 12
cm behind the lens. A glass plate 1cm thick, of refractive index 1.50 is
interposed between lens and film with its plane faces parallel to film. At
what distance (from lens) should object shifted to be in sharp focus of
film?
(a) 7.2 m
Page 3


PART-I (Single Correct MCQs)
1. A car is fitted with a convex side-view mirror of focal length 20 cm. A
second car 2.8 m behind the first car is overtaking the first car at a
relative speed of 15 m/s. The speed (in m/s) of the image of the second
car as seen in the mirror of the first one is :
(a) m/s
(b) 10 m/s
(c) 15 m/s
(d) m/s
2. If the refractive index of the material of a prism is  and the angle
of prism is A, then angle of minimum deviation is
(a) p – 2A
(b) p – A
(c)
(d)
3. A telescope has an objective of focal length 100 cm and an eyepiece of
focal length 5 cm. What is the magnifying power of the telescope when
the final image is formed at the least distance of distinct vision ?
(a) 20
(b) 24
(c) 28
(d) 3 2
4. In the figure shown, L is a converging lens of focal length 10 cm and M
is a concave mirror of radius of curvature 20cm. A point object O is
placed in front of the lens at a distance 15 cm. AB and CD are optical
axes of the lens and mirror respectively. The distance of the final image
formed by this system from the optical centre of the lens is cm.
Find the value of x in cm.
[The distance between CD and AB is 1 cm]
(a) 2
(b) 3
(c) 6
(d) 4
5. An object at 2.4 m in front of a lens forms a sharp image on a film 12
cm behind the lens. A glass plate 1cm thick, of refractive index 1.50 is
interposed between lens and film with its plane faces parallel to film. At
what distance (from lens) should object shifted to be in sharp focus of
film?
(a) 7.2 m
(b) 2.4 m
(c) 3.2 m
(d) 5.6 m
6. A transparent solid cylindrical rod has a refractive index of
 .
 It is
surrounded by air. A light ray is incident at the mid-point of one end of
the rod as shown in the figure.
The incident angle ? for which the light ray grazes along the wall of the rod is
:
(a)
(b)
(c)
(d) sin
–1
 (1/2)
7. A ray of light passes through an equilateral prism such that the angle of
incidence is equal to the angle of emergence and the latter is equal to 
th of angle of prism. The angle of deviation is
(a) 25°
(b) 30°
(c) 45°
(d) 35°
8. A light ray falls on a rectangular glass slab as shown. The index of
refraction of the glass, if total internal reflection is to occur at the
vertical face, is
(a)
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PART-I (Single Correct MCQs)
1. A car is fitted with a convex side-view mirror of focal length 20 cm. A
second car 2.8 m behind the first car is overtaking the first car at a
relative speed of 15 m/s. The speed (in m/s) of the image of the second
car as seen in the mirror of the first one is :
(a) m/s
(b) 10 m/s
(c) 15 m/s
(d) m/s
2. If the refractive index of the material of a prism is  and the angle
of prism is A, then angle of minimum deviation is
(a) p – 2A
(b) p – A
(c)
(d)
3. A telescope has an objective of focal length 100 cm and an eyepiece of
focal length 5 cm. What is the magnifying power of the telescope when
the final image is formed at the least distance of distinct vision ?
(a) 20
(b) 24
(c) 28
(d) 3 2
4. In the figure shown, L is a converging lens of focal length 10 cm and M
is a concave mirror of radius of curvature 20cm. A point object O is
placed in front of the lens at a distance 15 cm. AB and CD are optical
axes of the lens and mirror respectively. The distance of the final image
formed by this system from the optical centre of the lens is cm.
Find the value of x in cm.
[The distance between CD and AB is 1 cm]
(a) 2
(b) 3
(c) 6
(d) 4
5. An object at 2.4 m in front of a lens forms a sharp image on a film 12
cm behind the lens. A glass plate 1cm thick, of refractive index 1.50 is
interposed between lens and film with its plane faces parallel to film. At
what distance (from lens) should object shifted to be in sharp focus of
film?
(a) 7.2 m
(b) 2.4 m
(c) 3.2 m
(d) 5.6 m
6. A transparent solid cylindrical rod has a refractive index of
 .
 It is
surrounded by air. A light ray is incident at the mid-point of one end of
the rod as shown in the figure.
The incident angle ? for which the light ray grazes along the wall of the rod is
:
(a)
(b)
(c)
(d) sin
–1
 (1/2)
7. A ray of light passes through an equilateral prism such that the angle of
incidence is equal to the angle of emergence and the latter is equal to 
th of angle of prism. The angle of deviation is
(a) 25°
(b) 30°
(c) 45°
(d) 35°
8. A light ray falls on a rectangular glass slab as shown. The index of
refraction of the glass, if total internal reflection is to occur at the
vertical face, is
(a)
(b)
(c)
(d)
9. A person can see clearly only upto a distance of 30 cm. He
wants to read a book placed at a distance of 50 cm from his eyes. What
is the power of the lens of his spectacles ?
(a) –1.0 D
(b) –1.33 D
(c) –1.67 D
(d) –2.0 D
10. An observer can see through a pin-hole the top
end of a thin rod of height h, placed as shown in
the figure. The beaker height is 3h and its radius
h. When the beaker is filled with a liquid up to a
height 2h, he can see the lower end of the rod.
Then the refractive index of the
liquid is
(a)
(b)
(c)
(d)
11. A ray PQ incident on the refracting face BA is
refracted in the prism BAC as shown in the
figure and emerges from the other refracting
face AC as RS such that AQ = AR. If the angle
of prism A = 60° and the
Page 5


PART-I (Single Correct MCQs)
1. A car is fitted with a convex side-view mirror of focal length 20 cm. A
second car 2.8 m behind the first car is overtaking the first car at a
relative speed of 15 m/s. The speed (in m/s) of the image of the second
car as seen in the mirror of the first one is :
(a) m/s
(b) 10 m/s
(c) 15 m/s
(d) m/s
2. If the refractive index of the material of a prism is  and the angle
of prism is A, then angle of minimum deviation is
(a) p – 2A
(b) p – A
(c)
(d)
3. A telescope has an objective of focal length 100 cm and an eyepiece of
focal length 5 cm. What is the magnifying power of the telescope when
the final image is formed at the least distance of distinct vision ?
(a) 20
(b) 24
(c) 28
(d) 3 2
4. In the figure shown, L is a converging lens of focal length 10 cm and M
is a concave mirror of radius of curvature 20cm. A point object O is
placed in front of the lens at a distance 15 cm. AB and CD are optical
axes of the lens and mirror respectively. The distance of the final image
formed by this system from the optical centre of the lens is cm.
Find the value of x in cm.
[The distance between CD and AB is 1 cm]
(a) 2
(b) 3
(c) 6
(d) 4
5. An object at 2.4 m in front of a lens forms a sharp image on a film 12
cm behind the lens. A glass plate 1cm thick, of refractive index 1.50 is
interposed between lens and film with its plane faces parallel to film. At
what distance (from lens) should object shifted to be in sharp focus of
film?
(a) 7.2 m
(b) 2.4 m
(c) 3.2 m
(d) 5.6 m
6. A transparent solid cylindrical rod has a refractive index of
 .
 It is
surrounded by air. A light ray is incident at the mid-point of one end of
the rod as shown in the figure.
The incident angle ? for which the light ray grazes along the wall of the rod is
:
(a)
(b)
(c)
(d) sin
–1
 (1/2)
7. A ray of light passes through an equilateral prism such that the angle of
incidence is equal to the angle of emergence and the latter is equal to 
th of angle of prism. The angle of deviation is
(a) 25°
(b) 30°
(c) 45°
(d) 35°
8. A light ray falls on a rectangular glass slab as shown. The index of
refraction of the glass, if total internal reflection is to occur at the
vertical face, is
(a)
(b)
(c)
(d)
9. A person can see clearly only upto a distance of 30 cm. He
wants to read a book placed at a distance of 50 cm from his eyes. What
is the power of the lens of his spectacles ?
(a) –1.0 D
(b) –1.33 D
(c) –1.67 D
(d) –2.0 D
10. An observer can see through a pin-hole the top
end of a thin rod of height h, placed as shown in
the figure. The beaker height is 3h and its radius
h. When the beaker is filled with a liquid up to a
height 2h, he can see the lower end of the rod.
Then the refractive index of the
liquid is
(a)
(b)
(c)
(d)
11. A ray PQ incident on the refracting face BA is
refracted in the prism BAC as shown in the
figure and emerges from the other refracting
face AC as RS such that AQ = AR. If the angle
of prism A = 60° and the
refractive index of the material of prism is , then the angle of deviation of
the ray is
(a) 60°
(b) 45°
(c) 30°
(d) None of these
12. A rectangular glass slab ABCD of refractive
index n
1
 is immersed in water of refractive
index n
2
(n
1
 > n
2
). A ray of light is incident at
the surface AB of the slab as
shown. The maximum value of the angle of
incidence a
max
 such that the ray comes out only from the other surface
CD is given by
(a)
(b)
(c)
(d)
13. A microscope is focussed on a mark on a piece of paper and then a slab
of glass of thickness 3 cm and refractive index 1.5 is placed over the
mark. How should the microscope be moved to get the mark in focus
again ?
(a) 4.5 cm downward
(b) 1 cm downward
(c) 2 cm upward
(d) 1 cm upward
14. The focal lengths of the objective and the eye piece of a compound
microscope are 2.0 cm and 3.0 cm, respectively. The distance between