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# Refraction of Light: JEE Main(Part- 2) - Physics, Solution by DC Pandey NEET Notes | EduRev

## DC Pandey (Questions & Solutions) of Physics: NEET

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## NEET : Refraction of Light: JEE Main(Part- 2) - Physics, Solution by DC Pandey NEET Notes | EduRev

``` Page 1

Exercises
For JEE Main
Objective Questions
Single Correct Option
Q 1.  An endoscope is employed by a physician to view the internal parts of body organ. It is based on
the principle of
(a) refraction   (b) reflection  (c) total internal reflection  (d) dispersion
Q 2.  Refractive index ?

is given as
2
B
A ? ? ?
?
where A and B are constants and is wavelength, then
dimensions of B are same as that of
(a) wavelength  (b) volume  (c) pressure   (d) area
Q 3.  A plane glass slab is placed over various coloured letters. The letter which appears to be raised the
least is
(a) violet   (b) yellow  (c) red    (d) green
Q 4.  Critical angle of light passing from glass to air is least for
(a) red    (b) green   (c) yellow   (d) violet
Q 5.  The power in dioptre of an equi-convex lens with radii of curvature of 10 cm and refractive index
1.6 is
(a) +12   (b) +18   (c) +1.2   (d) +1.8
Q 6.  The refractive index of water is 4/3. The speed of light in water is
(a) 1.50 × 10
8
m/s  (b) 1.78 × 10
8
m/s (c) 2.25 × 10
8
m/s  (d) 2.67 × 10
8
m/s
Q 7.  White light is incident from under water on the water-air interface. If the angle of incidence is
slowly increased from zero, the emergent beam coming out into the air will turn from
(a) white to violet  (b) white to red (c) white to black  (d) None of these
Q 8.  When light enters from air to water, then its
(a) frequency increases and speed decreases
(b) frequency is same, but the wavelength is smaller in water than in air
(c) frequency is same but the wavelength in water is greater than in air
(d) frequency decreases and wavelength is smaller in water than in air
Q 9.  In the figure shown
sin i
sin r
is

equal to

(a)
2
2
31
?
??
(b)
3
1
?
?
(c)
31
2
2
??
?
(d)
1
3
?
?

Q 10.  In figure, the reflected ray B makes an angle 90° with the ray C. If i, r
1
and r
2
are the angles of
incidence, reflection and refraction, respectively. Then the critical angle of the medium is
Page 2

Exercises
For JEE Main
Objective Questions
Single Correct Option
Q 1.  An endoscope is employed by a physician to view the internal parts of body organ. It is based on
the principle of
(a) refraction   (b) reflection  (c) total internal reflection  (d) dispersion
Q 2.  Refractive index ?

is given as
2
B
A ? ? ?
?
where A and B are constants and is wavelength, then
dimensions of B are same as that of
(a) wavelength  (b) volume  (c) pressure   (d) area
Q 3.  A plane glass slab is placed over various coloured letters. The letter which appears to be raised the
least is
(a) violet   (b) yellow  (c) red    (d) green
Q 4.  Critical angle of light passing from glass to air is least for
(a) red    (b) green   (c) yellow   (d) violet
Q 5.  The power in dioptre of an equi-convex lens with radii of curvature of 10 cm and refractive index
1.6 is
(a) +12   (b) +18   (c) +1.2   (d) +1.8
Q 6.  The refractive index of water is 4/3. The speed of light in water is
(a) 1.50 × 10
8
m/s  (b) 1.78 × 10
8
m/s (c) 2.25 × 10
8
m/s  (d) 2.67 × 10
8
m/s
Q 7.  White light is incident from under water on the water-air interface. If the angle of incidence is
slowly increased from zero, the emergent beam coming out into the air will turn from
(a) white to violet  (b) white to red (c) white to black  (d) None of these
Q 8.  When light enters from air to water, then its
(a) frequency increases and speed decreases
(b) frequency is same, but the wavelength is smaller in water than in air
(c) frequency is same but the wavelength in water is greater than in air
(d) frequency decreases and wavelength is smaller in water than in air
Q 9.  In the figure shown
sin i
sin r
is

equal to

(a)
2
2
31
?
??
(b)
3
1
?
?
(c)
31
2
2
??
?
(d)
1
3
?
?

Q 10.  In figure, the reflected ray B makes an angle 90° with the ray C. If i, r
1
and r
2
are the angles of
incidence, reflection and refraction, respectively. Then the critical angle of the medium is

(a) sin
-1
(tan i)  (b) sin
-1
(cot i)  (c) r
1
(d) r
2

Q 11.  A prism of apex angle A = 60° has the refractive index 2 ?? . The angle of incidence for
minimum deviation is
(a) 30°   (b) 45°   (c) 60°   (d) None of these
Q 12.  A thin equi-convex lens is made of glass of refractive index 1.5 and its focal length is 0.2 m. If it
acts as a concave lens of 0.5 m focal length when dipped in a liquid, the refractive index of the
liquid is
(a)
17
8
(b)
15
8
(c)
13
8
(d)
9
8

Q 13.  A ray of light, travelling in a medium of refractive index ?, is incident at an angle i on a composite
transparent plate consisting of three plates of refractive indices ?
1
, ?
2
and ?
3
. The ray emerges
from the composite plate into a medium of refractive index ?
4
, at angle x. Then
(a) sin x = sin i  (b)
4
sin x sini
?
?
?
(c)
4
sin x sin i
?
?
?
(d)
13
224
sin x sini
? ? ?
?
???

Q 14.  The given equi-convex lens is broken into four parts and rearranged as shown. If the initial focal
length is f then after rearrangement, the equivalent focal length is

(a) f    (b) f/2    (c) f/4    (d) 4f
Q 15.  A thin convergent glass lens ( ?
g

= 1.5) has a power of + 5.0 D. When this lens is immersed in a
liquid of refractive index ?
l
, it acts as a divergent lens of focal length 100 cm. The value of ?
l

is
(a) 4/3    (b) 5/3    (c) 5/4    (d) 6/5
Q 16.  Two convex lenses of focal length 10 cm and 20 cm respectively placed coaxially and are
separated by some distance d. The whole system behaves like a concave lens . One of the possible
value of d is
(a) 15 cm   (b) 20 cm   (c) 25 cm   (d) 40 cm
Q 17.  A prism can have a maximum refracting angle of ( ?
c
= critical angle for the material of prism)
(a) 60°   (b) ?
c
(c) 2 ?
c
(d) slightly less than 180°
Page 3

Exercises
For JEE Main
Objective Questions
Single Correct Option
Q 1.  An endoscope is employed by a physician to view the internal parts of body organ. It is based on
the principle of
(a) refraction   (b) reflection  (c) total internal reflection  (d) dispersion
Q 2.  Refractive index ?

is given as
2
B
A ? ? ?
?
where A and B are constants and is wavelength, then
dimensions of B are same as that of
(a) wavelength  (b) volume  (c) pressure   (d) area
Q 3.  A plane glass slab is placed over various coloured letters. The letter which appears to be raised the
least is
(a) violet   (b) yellow  (c) red    (d) green
Q 4.  Critical angle of light passing from glass to air is least for
(a) red    (b) green   (c) yellow   (d) violet
Q 5.  The power in dioptre of an equi-convex lens with radii of curvature of 10 cm and refractive index
1.6 is
(a) +12   (b) +18   (c) +1.2   (d) +1.8
Q 6.  The refractive index of water is 4/3. The speed of light in water is
(a) 1.50 × 10
8
m/s  (b) 1.78 × 10
8
m/s (c) 2.25 × 10
8
m/s  (d) 2.67 × 10
8
m/s
Q 7.  White light is incident from under water on the water-air interface. If the angle of incidence is
slowly increased from zero, the emergent beam coming out into the air will turn from
(a) white to violet  (b) white to red (c) white to black  (d) None of these
Q 8.  When light enters from air to water, then its
(a) frequency increases and speed decreases
(b) frequency is same, but the wavelength is smaller in water than in air
(c) frequency is same but the wavelength in water is greater than in air
(d) frequency decreases and wavelength is smaller in water than in air
Q 9.  In the figure shown
sin i
sin r
is

equal to

(a)
2
2
31
?
??
(b)
3
1
?
?
(c)
31
2
2
??
?
(d)
1
3
?
?

Q 10.  In figure, the reflected ray B makes an angle 90° with the ray C. If i, r
1
and r
2
are the angles of
incidence, reflection and refraction, respectively. Then the critical angle of the medium is

(a) sin
-1
(tan i)  (b) sin
-1
(cot i)  (c) r
1
(d) r
2

Q 11.  A prism of apex angle A = 60° has the refractive index 2 ?? . The angle of incidence for
minimum deviation is
(a) 30°   (b) 45°   (c) 60°   (d) None of these
Q 12.  A thin equi-convex lens is made of glass of refractive index 1.5 and its focal length is 0.2 m. If it
acts as a concave lens of 0.5 m focal length when dipped in a liquid, the refractive index of the
liquid is
(a)
17
8
(b)
15
8
(c)
13
8
(d)
9
8

Q 13.  A ray of light, travelling in a medium of refractive index ?, is incident at an angle i on a composite
transparent plate consisting of three plates of refractive indices ?
1
, ?
2
and ?
3
. The ray emerges
from the composite plate into a medium of refractive index ?
4
, at angle x. Then
(a) sin x = sin i  (b)
4
sin x sini
?
?
?
(c)
4
sin x sin i
?
?
?
(d)
13
224
sin x sini
? ? ?
?
???

Q 14.  The given equi-convex lens is broken into four parts and rearranged as shown. If the initial focal
length is f then after rearrangement, the equivalent focal length is

(a) f    (b) f/2    (c) f/4    (d) 4f
Q 15.  A thin convergent glass lens ( ?
g

= 1.5) has a power of + 5.0 D. When this lens is immersed in a
liquid of refractive index ?
l
, it acts as a divergent lens of focal length 100 cm. The value of ?
l

is
(a) 4/3    (b) 5/3    (c) 5/4    (d) 6/5
Q 16.  Two convex lenses of focal length 10 cm and 20 cm respectively placed coaxially and are
separated by some distance d. The whole system behaves like a concave lens . One of the possible
value of d is
(a) 15 cm   (b) 20 cm   (c) 25 cm   (d) 40 cm
Q 17.  A prism can have a maximum refracting angle of ( ?
c
= critical angle for the material of prism)
(a) 60°   (b) ?
c
(c) 2 ?
c
(d) slightly less than 180°
Q 18.  A ray of light is incident at small angle I on the surface of prism of small angle A and emerges
normally from the opposite surface. If the refractive index of the material of the prism is ?,the
angle of incidence is nearly

equal to
(a)
A
?
(b)
A
2 ?
(c) ?A   (d) ?A/2
Q 19.  The refractive angle of a prism is A, and the refractive index of the material of the prism is cot (A
/2). The angle of minimum deviation is
(a) 180°-3A   (b) 180° + 2 A  (c) 90° - A   (d) 180° - 2A
Q 20.  A prism of refractive index 2 has refractive angle 60°. In order that a ray suffers minimum
deviation it should be incident at an angle of
(a) 45°   (b) 90°   (c) 30°   (d) None
Q 21.  The focal length of a combination of two lenses is doubled if the separation between them is
doubled. If the separation is increased to 4 times, the magnitude of focal length is
(a) doubled   (b) quadrupled  (c) halved   (d) same
Q 22.  A convexo-concave convergent lens is made of glass of refractive index 1.5 and focal length 24
cm. Radius of curvature for one surface is double than that of the other. Then radii of curvature for
the two surfaces are (in cm)
(a) 6, 12   (b) 12, 24  (c) 3, 6   (d) 18, 36
Q 23.  An optical system consists of a thin convex lens of focal length 30 cm and a plane mirror placed
15 cm behind the lens. An object is placed 15 cm in front of the lens. The distance of the final
image from the object is
(a) 60 cm   (b) 30 cm  (c) 75 cm   (d) 45 cm
Q 24.  In the figure shown the angle made by the light ray with the normal in the medium of refractive
index 2 is

(a) 30°   (b) 60°   (c) 90°   (d) None of the above
Q 25.  For refraction through a small angled prism, the angle of minimum deviation
(a) increases with increase in refractive index of a prism
(b) will be 2 ? for a ray of refractive index 2.4 if it is ? for a ray of refractive index 1.2
(c) is directly proportional to the angle of the prism
(d) will decrease with increase in refractive index of the prism
Q 26.  A ray of light passes from vacuum into a medium of refractive index n. If the angle of incidence is
twice the angle of refraction, then the angle of incidence is
(a) cos
-1
(n/2)   (b) sin
-1
(n/2)   (c) 2cos
-1
(n/2)  (d) 2sin
-1
(n/2)
Page 4

Exercises
For JEE Main
Objective Questions
Single Correct Option
Q 1.  An endoscope is employed by a physician to view the internal parts of body organ. It is based on
the principle of
(a) refraction   (b) reflection  (c) total internal reflection  (d) dispersion
Q 2.  Refractive index ?

is given as
2
B
A ? ? ?
?
where A and B are constants and is wavelength, then
dimensions of B are same as that of
(a) wavelength  (b) volume  (c) pressure   (d) area
Q 3.  A plane glass slab is placed over various coloured letters. The letter which appears to be raised the
least is
(a) violet   (b) yellow  (c) red    (d) green
Q 4.  Critical angle of light passing from glass to air is least for
(a) red    (b) green   (c) yellow   (d) violet
Q 5.  The power in dioptre of an equi-convex lens with radii of curvature of 10 cm and refractive index
1.6 is
(a) +12   (b) +18   (c) +1.2   (d) +1.8
Q 6.  The refractive index of water is 4/3. The speed of light in water is
(a) 1.50 × 10
8
m/s  (b) 1.78 × 10
8
m/s (c) 2.25 × 10
8
m/s  (d) 2.67 × 10
8
m/s
Q 7.  White light is incident from under water on the water-air interface. If the angle of incidence is
slowly increased from zero, the emergent beam coming out into the air will turn from
(a) white to violet  (b) white to red (c) white to black  (d) None of these
Q 8.  When light enters from air to water, then its
(a) frequency increases and speed decreases
(b) frequency is same, but the wavelength is smaller in water than in air
(c) frequency is same but the wavelength in water is greater than in air
(d) frequency decreases and wavelength is smaller in water than in air
Q 9.  In the figure shown
sin i
sin r
is

equal to

(a)
2
2
31
?
??
(b)
3
1
?
?
(c)
31
2
2
??
?
(d)
1
3
?
?

Q 10.  In figure, the reflected ray B makes an angle 90° with the ray C. If i, r
1
and r
2
are the angles of
incidence, reflection and refraction, respectively. Then the critical angle of the medium is

(a) sin
-1
(tan i)  (b) sin
-1
(cot i)  (c) r
1
(d) r
2

Q 11.  A prism of apex angle A = 60° has the refractive index 2 ?? . The angle of incidence for
minimum deviation is
(a) 30°   (b) 45°   (c) 60°   (d) None of these
Q 12.  A thin equi-convex lens is made of glass of refractive index 1.5 and its focal length is 0.2 m. If it
acts as a concave lens of 0.5 m focal length when dipped in a liquid, the refractive index of the
liquid is
(a)
17
8
(b)
15
8
(c)
13
8
(d)
9
8

Q 13.  A ray of light, travelling in a medium of refractive index ?, is incident at an angle i on a composite
transparent plate consisting of three plates of refractive indices ?
1
, ?
2
and ?
3
. The ray emerges
from the composite plate into a medium of refractive index ?
4
, at angle x. Then
(a) sin x = sin i  (b)
4
sin x sini
?
?
?
(c)
4
sin x sin i
?
?
?
(d)
13
224
sin x sini
? ? ?
?
???

Q 14.  The given equi-convex lens is broken into four parts and rearranged as shown. If the initial focal
length is f then after rearrangement, the equivalent focal length is

(a) f    (b) f/2    (c) f/4    (d) 4f
Q 15.  A thin convergent glass lens ( ?
g

= 1.5) has a power of + 5.0 D. When this lens is immersed in a
liquid of refractive index ?
l
, it acts as a divergent lens of focal length 100 cm. The value of ?
l

is
(a) 4/3    (b) 5/3    (c) 5/4    (d) 6/5
Q 16.  Two convex lenses of focal length 10 cm and 20 cm respectively placed coaxially and are
separated by some distance d. The whole system behaves like a concave lens . One of the possible
value of d is
(a) 15 cm   (b) 20 cm   (c) 25 cm   (d) 40 cm
Q 17.  A prism can have a maximum refracting angle of ( ?
c
= critical angle for the material of prism)
(a) 60°   (b) ?
c
(c) 2 ?
c
(d) slightly less than 180°
Q 18.  A ray of light is incident at small angle I on the surface of prism of small angle A and emerges
normally from the opposite surface. If the refractive index of the material of the prism is ?,the
angle of incidence is nearly

equal to
(a)
A
?
(b)
A
2 ?
(c) ?A   (d) ?A/2
Q 19.  The refractive angle of a prism is A, and the refractive index of the material of the prism is cot (A
/2). The angle of minimum deviation is
(a) 180°-3A   (b) 180° + 2 A  (c) 90° - A   (d) 180° - 2A
Q 20.  A prism of refractive index 2 has refractive angle 60°. In order that a ray suffers minimum
deviation it should be incident at an angle of
(a) 45°   (b) 90°   (c) 30°   (d) None
Q 21.  The focal length of a combination of two lenses is doubled if the separation between them is
doubled. If the separation is increased to 4 times, the magnitude of focal length is
(a) doubled   (b) quadrupled  (c) halved   (d) same
Q 22.  A convexo-concave convergent lens is made of glass of refractive index 1.5 and focal length 24
cm. Radius of curvature for one surface is double than that of the other. Then radii of curvature for
the two surfaces are (in cm)
(a) 6, 12   (b) 12, 24  (c) 3, 6   (d) 18, 36
Q 23.  An optical system consists of a thin convex lens of focal length 30 cm and a plane mirror placed
15 cm behind the lens. An object is placed 15 cm in front of the lens. The distance of the final
image from the object is
(a) 60 cm   (b) 30 cm  (c) 75 cm   (d) 45 cm
Q 24.  In the figure shown the angle made by the light ray with the normal in the medium of refractive
index 2 is

(a) 30°   (b) 60°   (c) 90°   (d) None of the above
Q 25.  For refraction through a small angled prism, the angle of minimum deviation
(a) increases with increase in refractive index of a prism
(b) will be 2 ? for a ray of refractive index 2.4 if it is ? for a ray of refractive index 1.2
(c) is directly proportional to the angle of the prism
(d) will decrease with increase in refractive index of the prism
Q 26.  A ray of light passes from vacuum into a medium of refractive index n. If the angle of incidence is
twice the angle of refraction, then the angle of incidence is
(a) cos
-1
(n/2)   (b) sin
-1
(n/2)   (c) 2cos
-1
(n/2)  (d) 2sin
-1
(n/2)
Q 27.  A thin convex lens of focal length 30 cm is placed in front of a plane mirror. An object is placed at
a distance x from the lens (not in between lens and mirror) so that its final image coincide with
itself. Then, the value of x is
(a) 15 cm   (b) 30 cm   (c) 60 cm   (d) Insufficient data
Q 28.  One side of a glass slab is silvered as shown in the figure. A ray of light is incident on the other
side at angle of incidence 45°. Refractive index of glass is given as 2 .

The deflection suffered
by the ray when it comes out of the slab is

(a) 90°   (b) 180°  (c) 120°   (d) 45°
Q 29.  A prism has refractive index
3
2
and refractive angle 90°. Find the minimum deviation produced
by prism
(a) 60°   (b) 45°   (c) 30°   (d) 15°
Q 30.  In figure, an air lens of radius of curvature of each surface equal to 10 cm is cut in a cylinder of
glass of refractive index 1.5. The focal length and the nature of lens are

(a) 15 cm diverging  (b) 15 cm converging (c) 10 cm diverging  (d) 10 cm converging
Q 31.  A point object is placed at a distance of 12 cm from a convex lens of focal length 10 cm. On the
other side of the lens, a convex mirror is placed at a distance of 10 cm from the lens such that the
image formed by the combination coincides with the object itself. The focal length of the convex
mirror is
(a) 20 cm   (b) 25 cm  (c) 15 cm   (d) 30 cm
Q 32.  An object, a convex lens of focal length 20 cm and a plane mirror are arranged as shown in the
figure. How far behind the mirror is the second image formed ?

(a) 30 cm  (b) 20 cm  (c) 40 cm  (d) 50 cm
Q 33.  Two parallel light rays pass through an isosceles prism of refractive index
3
2
as shown in figure.
The angle between the two emergent rays is
Page 5

Exercises
For JEE Main
Objective Questions
Single Correct Option
Q 1.  An endoscope is employed by a physician to view the internal parts of body organ. It is based on
the principle of
(a) refraction   (b) reflection  (c) total internal reflection  (d) dispersion
Q 2.  Refractive index ?

is given as
2
B
A ? ? ?
?
where A and B are constants and is wavelength, then
dimensions of B are same as that of
(a) wavelength  (b) volume  (c) pressure   (d) area
Q 3.  A plane glass slab is placed over various coloured letters. The letter which appears to be raised the
least is
(a) violet   (b) yellow  (c) red    (d) green
Q 4.  Critical angle of light passing from glass to air is least for
(a) red    (b) green   (c) yellow   (d) violet
Q 5.  The power in dioptre of an equi-convex lens with radii of curvature of 10 cm and refractive index
1.6 is
(a) +12   (b) +18   (c) +1.2   (d) +1.8
Q 6.  The refractive index of water is 4/3. The speed of light in water is
(a) 1.50 × 10
8
m/s  (b) 1.78 × 10
8
m/s (c) 2.25 × 10
8
m/s  (d) 2.67 × 10
8
m/s
Q 7.  White light is incident from under water on the water-air interface. If the angle of incidence is
slowly increased from zero, the emergent beam coming out into the air will turn from
(a) white to violet  (b) white to red (c) white to black  (d) None of these
Q 8.  When light enters from air to water, then its
(a) frequency increases and speed decreases
(b) frequency is same, but the wavelength is smaller in water than in air
(c) frequency is same but the wavelength in water is greater than in air
(d) frequency decreases and wavelength is smaller in water than in air
Q 9.  In the figure shown
sin i
sin r
is

equal to

(a)
2
2
31
?
??
(b)
3
1
?
?
(c)
31
2
2
??
?
(d)
1
3
?
?

Q 10.  In figure, the reflected ray B makes an angle 90° with the ray C. If i, r
1
and r
2
are the angles of
incidence, reflection and refraction, respectively. Then the critical angle of the medium is

(a) sin
-1
(tan i)  (b) sin
-1
(cot i)  (c) r
1
(d) r
2

Q 11.  A prism of apex angle A = 60° has the refractive index 2 ?? . The angle of incidence for
minimum deviation is
(a) 30°   (b) 45°   (c) 60°   (d) None of these
Q 12.  A thin equi-convex lens is made of glass of refractive index 1.5 and its focal length is 0.2 m. If it
acts as a concave lens of 0.5 m focal length when dipped in a liquid, the refractive index of the
liquid is
(a)
17
8
(b)
15
8
(c)
13
8
(d)
9
8

Q 13.  A ray of light, travelling in a medium of refractive index ?, is incident at an angle i on a composite
transparent plate consisting of three plates of refractive indices ?
1
, ?
2
and ?
3
. The ray emerges
from the composite plate into a medium of refractive index ?
4
, at angle x. Then
(a) sin x = sin i  (b)
4
sin x sini
?
?
?
(c)
4
sin x sin i
?
?
?
(d)
13
224
sin x sini
? ? ?
?
???

Q 14.  The given equi-convex lens is broken into four parts and rearranged as shown. If the initial focal
length is f then after rearrangement, the equivalent focal length is

(a) f    (b) f/2    (c) f/4    (d) 4f
Q 15.  A thin convergent glass lens ( ?
g

= 1.5) has a power of + 5.0 D. When this lens is immersed in a
liquid of refractive index ?
l
, it acts as a divergent lens of focal length 100 cm. The value of ?
l

is
(a) 4/3    (b) 5/3    (c) 5/4    (d) 6/5
Q 16.  Two convex lenses of focal length 10 cm and 20 cm respectively placed coaxially and are
separated by some distance d. The whole system behaves like a concave lens . One of the possible
value of d is
(a) 15 cm   (b) 20 cm   (c) 25 cm   (d) 40 cm
Q 17.  A prism can have a maximum refracting angle of ( ?
c
= critical angle for the material of prism)
(a) 60°   (b) ?
c
(c) 2 ?
c
(d) slightly less than 180°
Q 18.  A ray of light is incident at small angle I on the surface of prism of small angle A and emerges
normally from the opposite surface. If the refractive index of the material of the prism is ?,the
angle of incidence is nearly

equal to
(a)
A
?
(b)
A
2 ?
(c) ?A   (d) ?A/2
Q 19.  The refractive angle of a prism is A, and the refractive index of the material of the prism is cot (A
/2). The angle of minimum deviation is
(a) 180°-3A   (b) 180° + 2 A  (c) 90° - A   (d) 180° - 2A
Q 20.  A prism of refractive index 2 has refractive angle 60°. In order that a ray suffers minimum
deviation it should be incident at an angle of
(a) 45°   (b) 90°   (c) 30°   (d) None
Q 21.  The focal length of a combination of two lenses is doubled if the separation between them is
doubled. If the separation is increased to 4 times, the magnitude of focal length is
(a) doubled   (b) quadrupled  (c) halved   (d) same
Q 22.  A convexo-concave convergent lens is made of glass of refractive index 1.5 and focal length 24
cm. Radius of curvature for one surface is double than that of the other. Then radii of curvature for
the two surfaces are (in cm)
(a) 6, 12   (b) 12, 24  (c) 3, 6   (d) 18, 36
Q 23.  An optical system consists of a thin convex lens of focal length 30 cm and a plane mirror placed
15 cm behind the lens. An object is placed 15 cm in front of the lens. The distance of the final
image from the object is
(a) 60 cm   (b) 30 cm  (c) 75 cm   (d) 45 cm
Q 24.  In the figure shown the angle made by the light ray with the normal in the medium of refractive
index 2 is

(a) 30°   (b) 60°   (c) 90°   (d) None of the above
Q 25.  For refraction through a small angled prism, the angle of minimum deviation
(a) increases with increase in refractive index of a prism
(b) will be 2 ? for a ray of refractive index 2.4 if it is ? for a ray of refractive index 1.2
(c) is directly proportional to the angle of the prism
(d) will decrease with increase in refractive index of the prism
Q 26.  A ray of light passes from vacuum into a medium of refractive index n. If the angle of incidence is
twice the angle of refraction, then the angle of incidence is
(a) cos
-1
(n/2)   (b) sin
-1
(n/2)   (c) 2cos
-1
(n/2)  (d) 2sin
-1
(n/2)
Q 27.  A thin convex lens of focal length 30 cm is placed in front of a plane mirror. An object is placed at
a distance x from the lens (not in between lens and mirror) so that its final image coincide with
itself. Then, the value of x is
(a) 15 cm   (b) 30 cm   (c) 60 cm   (d) Insufficient data
Q 28.  One side of a glass slab is silvered as shown in the figure. A ray of light is incident on the other
side at angle of incidence 45°. Refractive index of glass is given as 2 .

The deflection suffered
by the ray when it comes out of the slab is

(a) 90°   (b) 180°  (c) 120°   (d) 45°
Q 29.  A prism has refractive index
3
2
and refractive angle 90°. Find the minimum deviation produced
by prism
(a) 60°   (b) 45°   (c) 30°   (d) 15°
Q 30.  In figure, an air lens of radius of curvature of each surface equal to 10 cm is cut in a cylinder of
glass of refractive index 1.5. The focal length and the nature of lens are

(a) 15 cm diverging  (b) 15 cm converging (c) 10 cm diverging  (d) 10 cm converging
Q 31.  A point object is placed at a distance of 12 cm from a convex lens of focal length 10 cm. On the
other side of the lens, a convex mirror is placed at a distance of 10 cm from the lens such that the
image formed by the combination coincides with the object itself. The focal length of the convex
mirror is
(a) 20 cm   (b) 25 cm  (c) 15 cm   (d) 30 cm
Q 32.  An object, a convex lens of focal length 20 cm and a plane mirror are arranged as shown in the
figure. How far behind the mirror is the second image formed ?

(a) 30 cm  (b) 20 cm  (c) 40 cm  (d) 50 cm
Q 33.  Two parallel light rays pass through an isosceles prism of refractive index
3
2
as shown in figure.
The angle between the two emergent rays is

(a) 15°   (b) 30°   (c) 45°   (d) 60°
Q 34.  A prism having refractive index 2 and refractive angle 30° has one of the refractive surfaces
polished. A beam of light incident on the other surface will trace its path if the angle of incidence
is
(a) 0°    (b) 30°   (c) 45°   (d) 60°
Q 35.  In Fig. (i), a lens of focal length 10 cm is shown. It is cut into two parts and placed as shown in
Fig. (ii). An object AB of height 1 cm is placed at a distance of 7.5 cm. The height of the image
will be

(a) 2 cm   (b) 1 cm  (c) 1.5 cm   (d) 3 cm
Q 36.  The image for the converging beam after refraction through the curved surface is formed at

(a) x = 40 cm   (b) x = 40/3 cm (c) x = - 40/3 cm  (d) x = 20 cm
Q 37.  A concavo-convex lens is made of glass of refractive index 1.5. The radii of curvature of its two
surfaces are 30 cm and 50 cm. Its focal length when placed in a liquid of refractive index 1.4 is
(a) 200 cm   (b) 500 cm  (c) 800 cm   (d) 1050 cm
Q 38.  From the figure shown establish a relation between ?
1
, ?
2
and ?
3

(a) ?
1
< ?
2
< ?
3
(b) ?
3
< ?
2
; ?
3
= ?
1
(c) ?
3
> ?
2
; ?
3
= ?
1
(d) None of these
Q 39.  When light of wavelength is incident on an equilateral prism, kept on its minimum deviation
position, it is found that the angle of deviation equals the angle of the prism itself. The refractive
index of the material of the prism for the wavelength is
(a) 3   (b) 3/ 2   (c) 2   (d) 2
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