RAY OPTICS
(I) REFRACTION OF LIGHT AT PLANE SURFACES
1.
9
The refractive index of glass with respect to water is   . Refractive index of glass with
8
3
respect to air is   . Then refractive index of water with respect to air will be
2
(1)
2.
3.
8
9
(1) 3840 Aº ; 3 X 108 m/s
(2) 5760 Aº ; 2.4 X 108 m/s
(3) 6420 Aº ; 2.2 X 108 m/s
(4) 8460 Aº ; 2.6 X 108 m/s
4
Then 1  3 is equal to
(1) 2
9
(2) 8
8
(3) 9
5
(4) 3
A monochromatic light beam of frequency 6 X 1014 Hz passes from air into a transparent
medium where its wave length is found to be 300nm. The refractive index of medium is
(1)
6.
9
(4) 4
There are three transparent media. The relative refractive indices are, 1  2 = 3 and 2 3 =
2
5.
4
(3) 3
A monochromatic light of wave length 7200 Aº in air enters into a transparent medium of
refractive index µ = 1.25. The wave length and speed of the light in the medium will be
3
4.
8
(2)3
4
3
7
(2) 5
3
(3) 2
5
(4) 3
A monochromatic light beam of light of wave length 6000 A0 enters from air into a
5
transparent liquid of relative R.I, a  l = 3. The wave length and frequency of the light
beam in the liquid will be
(1) 7200A0 ; 4 X 1014Hz
(2) 6800 A0 ; 3.6 X 1014Hz
(3) 3600A0 ; 5 X 1014Hz
(4) 4800A0 ; 6 X 1014Hz
The absolute refractive index of air 1.0003. The thickness of air column, in mm, which
has six more wave lengths of monochromatic light of wave length 4000A0 than in the
same thickness of vacuum will be
(1) 3mm
(2) 5mm
(3) 6mm
(4) 8mm
7.
5
A light ray is incident on a transparent slab of refractive index µ = 3. The light ray is
partly reflected and partly refracted. The reflected and refracted rays are at right angles to
each other. The angle of incidence of light ray on the slab is
5
(1) tan-1  
3
8.
3
(4) VA < VB < VC
(2) 2
5
(3) 3
6
(4) 5
(2) 2.8
(3) 1.2
(4) 0.8
(2) 0.4
(3) 0.8
(4) 1.8
The X – Z plane separates two transparent media ‘A’ and ‘B’. The refractive indices µA =
1.8 and µB =1.2 A light ray travels from ‘A’ to ‘B’. Its directions in the two media are
given by the unit vectors U1 = a iˆ +b ĵ and U 2 = c iˆ + ĵ then
(1)
13.
(3) VA < VB = VC
The same monochromatic light traverses through a distance of 300m in two transparent
media of refractive indices 1.4 and 1.8 in turn. The difference in the times of traversal in
the two media, in, microsecond, is
(1) 1.6
12.
(2) VA = VB = VC
A monochromatic light traverses through water column of length 90m. If R.I of water is
4
, the time taken by light to traverse this distance, in, microsecond, is
3
(1) 3.6
11.
3
(4) sin-1  
5
A transparent slab of thickness 6cm contains the same number of monochromatic light
4
waves as water column of thickness 9cm. If refractive index of water is 3, then that of
material of slab is
(1) 2
10.
3
(3) cos-1  
5
For a particular angle of incidence of a light ray, the angles of refraction in three
transparent media A,B, and C are 150 450 and 600 respectively. The speeds of light in the
three media VA,, VB and VC are related as
(1) VA > VB > VC
9.
(2) 600
a 4

c 3
(2)
b 3

d 4
(3)
b 3

d 2
(4)
a 3

c 2
The bottom of a glass beaker containing a liquid appears to raise by 5cm. on increasing
the liquid level is beaker by 9cm, the bottom appears to rise by 8cm. The refractive index
of liquid is
(1)
3
2
(2)
4
3
(3)
5
6
(4)
7
5
14.
A glass breaker has a layer of colored water of thickness 5cm whose refractive index is
5
. A layer of oil of thickness 3cm floats on water layer. When observed normally from
3
20
above in air, the total apparent shift of a spot at the bottom of beaker is found to be
7
cm. The refractive index of oil is
(1)
15.
5
4
(2)
9
5
(2) 22CM
(3) 29CM
(4) 32CM
(2) 26cm
(3) 74cm
(4) 82cm
4
3
(2)
5
3
(3)
7
5
(4)
3
2
A small pin is placed erect 20cm in front of a transparent slab of thickness 10cm. The
farther face of slab is silvered. The image of pin is formed 22cm behind the silvered face.
The refractive index of material of slab is
(1)
19.
(4)
A transparent cube of side 24cm has a small air bubble. When viewed from one face of
cube, the bubble appears to be 10cm from the face. When viewed from the opposite face
it is 6cm from the face. The refractive index of material of cube is
(1)
18.
7
5
As fish is at a depth of 50cm from the surface of a lake. It sees a bird directly overhead.
The bird is at an actual height of 24cm above water surface. The height of bird above
4
water surface as seen by fish in water will be (R.I of water is )
3
(1) 32cm
17.
(3)
A glass beaker contains three layers of immiscible liquids A, B and C of refractive
4 5
9
indices ,
and . Their respective thicknesses are 8cm, 10cm and 18cm. When
3 3
5
observed of normally from above in air, the apparent depth of bottom of beaker will be
(1) 17CM
16.
5
3
3
2
(2)
5
3
(3)
7
5
(4)
9
5
A parallel sided slab has thickness 18cm. A ray light gets refracted at air – glass interface
of the slab. The angles of incidence and refraction are 600 and 300 respectively. The
lateral shift suffered by the light ray while emerging from the slab will be
(1)
3cm
(2) 6cm
(3) 6 3cm
(4) 3 3cm
20.
A fish rising up vertically at uniform speed of 4m/s finds a bird diving vertically towards
4
water surface at uniform speed of 12m/s. If refractive index of water is , then the actual
3
velocity of dive of bird will be
(1) 10m/s
21.
(2) 8m/s
3
4
(2) cos-1  
(2) 6cm
(3) 8cm
(3)
1a
a b
2
(4) 12cm
(2) µ1= (a2+b2) = µ2(c2+d2)
2

2d
c d
2
2



(4) 1b a 2  b 2  2c c 2  d 2

A fish in a lake can observe outside world through a circular aperture of radius ‘r’ at
surface. If the fish is situated 14m below surface of water and refractive index of water is
4
, then radius ‘r’ is equal to
3
(1) 3 3m
25.
8
5
(4) cot-1  
Two thin transparent slabs of refractive indices µ1 and µ2 are placed parallel to each other in
the X – Z plane. If the directions of propagation of a light ray in the two slabs are along
the vectors r 1 = a iˆ + b ĵ and r 2 = c iˆ + d ĵ , then
(1) µ1a = µ2b
24.
4
3
(3) tan-1  
A tank contains a glass slab of thickness 8cm and of refractive index 1.6. Above this is a
liquid layer of thickness4.5cm and of refractive index 1.5. Upon this layer floats water
4
layer of thickness 6cm and of refractive index . To an observer looking from above in
3
air, the position of a mark on the bottom of tank appears to be raised by
(1) 4cm
23.
(4) 6m/s
The speeds of light in two transparent media A and B are 1.8 X 108m/s and 2.4 X 108m/s
respective. The critical angle for a light ray incident at the interface of two media is
3
(1) sin-1  
4
22.
(3) 7.5m/s
(2) 4 2m
(3) 6 3m
(4) 6 7 m
A small source of light is situated at the bottom of a pool of water of refractive index µ
and depth h. The source emits light rays in all directions so that a circle of light is formed
on the surface of water. The area of circle is
(1)
h 2
 2 1
(2)
 (  2  1)
h2
(3) h 2
(4) h 2 (  2  1)
26.
A point source of light is placed at the bottom of a water tank of depth ‘h’. The refractive
index of water is ‘µ’. The fraction of light energy that emerges from surface of water
into air is
(1)
27.

   1
h
 2 1
(2) 110
(3) 490
(4)70
(2) 14.6cm
(3) 13.6cm
(4) 12.5cm
(2) 1.6
(3) 1.4
(4) 1.2
(2)   2 c
(3) 2 c
(4)

2
 c
A ray of light travelling in a transparent from air, at an angle of incidence of 450. The
light ray undergoes total internal reflection. It ‘µ’ is the refractive index of medium with
respect to air, then the possible value of “µ” is
(1) 1.2
32.
(4)
A ray of light travels from are optically denser to rarer medium. The critical angle for the
two media is  c. the maximum possible deviation of the light ray will be
(1)    c
31.
2h   1
2
   2 1
2
A parallel beam of light rays of width 20cm passes from glass to air. The width of beam
in air is 10scm. The refractive index of glass is nearly.
(1) 1.8
30.
(3)
A parallel beam of light rays of width 18cm passes from glass of refractive index µ = 1.6
into air at an angle of incidence of 300. The width of the light beam in air is nearly.
(1) 16.2cm
29.

The refractive index of glass 1.5. The angle of deviation of a light ray passing from air to
1
glass at an angle of incidence 300 (take sin1   = 190) is
3
(1) 210
28.
2
(2)
(2) 1.3
(3) 1.4
(4) 1.6
The critical angle for a transparent liquid relative to air is 300. The speed of light in the
liquid is
(1) 2.4 X 108m/s
(2) 2 X 108m/s
(3) 1.5 X 108m/c
(4)1.2 X 108m/s
33.
A monochromatic light ray travels in two transparent media ‘A’ and ‘B’ with speeds of
2.4 X 108m/s and 1.92 X 108m/s. If the light ray undergoes total internal reflection, then
the angle of incidence is the denser medium can be
(1) 150
34.
(3) 450`
(4) 600
When a ray of light travels from medium ‘A’ to medium ‘B’ it velocity get doubled. The
maximum value of angle of incidence in optically denser medium so that total internal
reflection does not take place will be
(1) 300
35.
(2) 300
(2) 450
(3) 600
(4) 750
In an optical fiber the core of refractive index 1.8 is surrounded by a glass cladding of
refractive index 1.6. The critical angle for total internal reflection at the core – cladding
interface is
3
(1) sin 1  
5
 10 

 75 
(2) sin 1 
 40 

 45 
(3) sin 1 
3
4
(4) sin 1  