Medical Sample papers

Ray Optics Problems and Answers

PHYSICS RAY OPTICS

Ray Optics Questions and Answers

Question 1
A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens.  Then its focal length will
A
Remain unchanged
B
Become zero
C
Become small, but non–zero
D
Become infinite
Question 2
Line spectrum was first of all theoretically explained by
A
Fraunhofer
B
Bohr
C
Swan
D
Kirchoff
Question 3
The fine powder of a coloured glass is seen as
A
Black
B
Coloured
C
That of the glass colour
D
White
Question 4
When a plane mirror is placed horizontally on a level ground at a distance of 60 m from the foot of a tower, the top of the tower and its image in the mirror subtend an angle of 90o at the eye. The height of the tower will be
A
90 m
B
60 m
C
30 m
D
120 m
Question 5
A lamp is hanging at a height of 4m above a table. The lamp is lowered by 1m. The percentage increase in illuminace will be
A
64%
B
92%
C
40 %
D
78%
Question 6
Line spectrum contains information about

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A
The atoms as well as molecules of the source
B
The atoms of the prism
C
The molecules of the source
D
The atoms of the source
Question 7
A lamp is hanging at a height 40 cm from the centre of a table. If its height is increased by 10 cm the illuminance on the table will decrease by
A
20%
B
36%
C
27%
D
10 %
Question 8
In order to obtain a real image of magnification 2  using a converging lens of focal length 20 cm, where should an object be placed
A
50 cm
B
30 cm
C
– 30 cm
D
– 50 cm
Question 9
Colour of the sky is blue due to
A
None of these
B
Total emission
C
Scattering of light
D
Total internal reflection
Question 10
A neon sign does not produce
A
An absorption spectrum
B
Photons
C
An emission spectrum
D
Line spectrum
Question 11
The radius of curvature of convex surface of a thin plano-convex lens is 15 cm and refractive index of its material is 1.6. The power of the lens will be
A
–2D
B
+1 D
C
+4 D
D
+3 D
Question 12
The length of a telescope is 36 cm. The focal lengths of its lenses can be
A
30 cm, – 6 cm
B
– 30 cm, 6 cm
C
– 30 cm, – 6 cm
D
30 cm, 6 cm
Question 13
The number of wavelengths in the visible spectrum
A
2000
B
6000
C
Infinite
D
4000
Question 14
For a normal eye, the least distance of distinct vision is
A
0.50 m
B
Infinite
C
25 m
D
0.25 m
Question 15
Chromatic aberration of lens can be corrected by
A
Reducing its aperature
B
Proper polishing of its two surfaces
C
Providing different suitable curvature to its two surfaces
D
Suitably combining it with another lens
Question 16
The magnifying power of a simple microscope can be increased, if we use eye-piece of
A
Higher focal length
B
Smaller focal length
C
Higher diameter
D
Smaller diameter
Question 17
Under minimum deviation condition in a prism, if a ray is incident at an angle 30o, the angle between the emergent ray and the second refracting surface of the prism is
A
B
60°
C
45°
D
30°
Question 18
In a compound microscope cross-wires are fixed at the point
A
Where the focal point of the eye-piece lies
B
Where the image is formed by the objective
C
Where the image is formed by the eye-piece
D
Where the focal point of the objective lies
Question 19
A thin equiconvex 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

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A
13/8
B
15/8
C
17/8
D
9/8
Question 20
A symmetric double convex lens is cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens was 4 D, the power of a cut lens will be
A
4 D
B
3 D
C
5 D
D
2 D
Question 21
A converging lens is used to form an image on a screen. When upper half of the lens is covered by an opaque screen
A
Complete image will be formed of same intensity
B
Half the image will disappear
C
Half image will be formed of same intensity
D
Complete image will be formed of decreased intensity
Question 22
Relative difference of focal lengths of objective and eye lens in the microscope and telescope is given as
A
It is more in telescope
B
It is equal in both
C
It may be more in any one
D
It is more in microscope
Question 23
On which of the following does the magnifying power of a telescope depends
A
The diameter of aperture of the objective and that of the eye piece
B
The focal length of the objective and that of the eye piece
C
The diameter of aperture of the objective only
D
The focal length of the objective only
Question 24
The dispersive powers of glasses of lenses used in an achromatic pair are in the ratio 5 : 3. If the focal length of the concave lens is 15 cm, then the nature and focal length of the other lens would be

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A
Concave,  25 cm
B
Convex, 25 cm
C
Concave, 9 cm
D
Convex, 9 cm
Question 25
An object has image thrice of its original size when kept at 8 cm and 16 cm from a convex lens.  Focal length of the lens is
A
16 cm
B
Between 8 cm and 16 cm
C
8 cm
D
Less than 8 cm
Question 26
An eye specialist prescribes spectacles having a combination of convex lens of focal length 40 cm in contact with a concave lens of focal length 25 cm. The power of this lens combination in diopters is
A
– 1.5
B
– 6.67
C
+ 1.5
D
+ 6.67
Question 27
The critical angle for diamond (refractive index = 2) is
A
60°
B
About 20°
C
30°
D
45°
Question 28
A convex lens, a glass slab, a glass prism and a solid sphere all are made of the same glass, the dispersive power will be
A
Only in prism
B
In all the four
C
In the lens and solid sphere
D
In the glass slab and prism
Question 29
If refractive index of red, violet and yellow lights are 1.42, 1.62 and 1.50 respectively for a medium. Its dispersive power will be
A
0.3
B
0.4
C
0.1
D
0.2
Question 30
An imaginary line joining the optical centre of the eye lens and the yellow point is called as

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A
Neutral axis
B
Vision axis
C
Principal axis
D
Optical axis
Question 31
Five lumen/watt is the luminous efficiency of a lamp and its luminous intensity is 35 candela. The power of the lamp is
A
176 W
B
80 W
C
88 W
D
36 W
Question 32
Ability of the eye to see objects at all distances is called
A
Hypermetropia
B
Myopia
C
Accommodation
D
Binocular vision
Question 33
Which source is associated with a line emission spectrum?
A
Neon street sign
B
Sun
C
Electric fire
D
Red traffic light
Question 34
A compound microscope has two lenses. The magnifying power of one is 5 and the combined magnifying power is 100. The magnifying power of the other lens is

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A
20
B
50
C
10
D
25
Question 35
Retina of eye acts like ........ of camera
A
None of these
B
Shutter
C
Film
D
Lens
There are 35 questions to complete.

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