Optics Online Test 10th science lesson 2 Questions in English

Optics Online Test 10th science lesson 2 Questions in English

Congratulations - you have completed Optics Online Test 10th science lesson 2 Questions in English. You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%
Your answers are highlighted below.
Question 1
Which of the following statement is correct?
  1. Light is a form of energy which travels in the form of waves
  2. The path of light is called ray of light and group of these rays are called as beam of light.
  3. Any object which gives out light are termed as source of light and is called as luminous objects
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 1 Explanation: 
Light is a form of energy which travels in the form of waves. The path of light is called ray of light and group of these rays are called as beam of light. Any object which gives out light are termed as source of light. Some of the sources emit their own light and they are called as luminous objects. All the stars, including the Sun, are examples for luminous objects.
Question 2
Which of the following statement about properties of light is correct?
  1. Light is a form of energy.
  2. Light always travels in a Zig Zag manner
  3. When light is incident on the interface between two media, it is partly reflected and partly refracted
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 2 Explanation: 
Explanation PROPERTIES OF LIGHT: Light is a form of energy Light always travels along a straight line. When light is incident on the interface between two media, it is partly reflected and partly refracted. Th e speed of light can be calculated using the following equation: c = ν λ (c - velocity of light).
Question 3
  • Assertion(A): Light can even travel through vacuum.
  • Reason(R): Light does not need any medium for its propagation.
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is Correct and (R) is wrong
Question 3 Explanation: 
Light does not need any medium for its propagation. It can even travel through vacuum. The speed of light in vacuum or air is, c = 3 × 10^8 m/s. Since, light is in the form of waves, it is characterized by a wavelength (λ) and a frequency (ν), which are related by the following equation: c = ν λ (c - velocity of light).
Question 4
Which of the following light has lowest wavelength?
A
Green
B
Red
C
Violet
D
Yellow
Question 4 Explanation: 
Different coloured light has different wavelength and frequency. Among the visible light, violet light has the lowest wavelength and red light has the highest wavelength.
Question 5
The deviation of ray of light is called_____
A
Reflection
B
Depression
C
Refraction
D
None
Question 5 Explanation: 
When a ray of light travels from one transparent medium into another obliquely, the path of the light undergoes deviation. This deviation of ray of light is called refraction.
Question 6
Which of the following statement is correct?
A
The velocity of light is more in a rarer medium and less in a denser medium
B
The velocity of light is less in a rarer medium and more in a denser medium
C
The velocity of light is same in both rarer medium and in denser medium
D
None
Question 6 Explanation: 
Refraction takes place due to the difference in the velocity of light in different media. The velocity of light is more in a rarer medium and less in a denser medium. Refraction of light obeys two laws of refraction.
Question 7
According to First law of refraction which of the following lie in the same plane?
  1. Incident ray
  2. Reflected ray
  3. Refracted ray
  4. Normal
A
1, 3, 4
B
2, 3, 4
C
1, 2, 4
D
All the above
Question 7 Explanation: 
First law of refraction: According to first law of refraction, the incident ray, the refracted ray of light and the normal to the refracting surface all lie in the same plane.
Question 8
Which of the following statement is incorrect?
  1. Second law of refraction is also known as Snell’s law
  2. Refractive index gives us an idea of how fast or how slow light travels in a medium
A
1 alone
B
2 alone
C
1, 2
D
None
Question 8 Explanation: 
Second law of refraction: The ratio of the sine of the angle of incidence and sine of the angle of refraction is equal to the ratio of refractive indices of the two media. This law is also known as Snell’s law. Refractive index gives us an idea of how fast or how slow light travels in a medium. The ratio of speed of light in vacuum to the speed of light in a medium is defined as refractive index ‘µ’ of that medium.
Question 9
The speed of light in a medium is___ if the refractive index of the medium is____
A
High, Low
B
Low, High
C
Low, low
D
Both a and b
Question 9 Explanation: 
The speed of light in a medium is low if the refractive index of the medium is high and vice versa. The above statement is drawn out of Second law of refraction or Snell’s law.
Question 10
Which of the following statement is incorrect?
  1. When light travels from a denser medium into a rarer medium, the refracted ray is bent towards from the normal drawn to the interface
  2. When light travels from a rarer medium into a denser medium, the refracted ray is bent away from the normal drawn to the interface.
A
1 alone
B
2 alone
C
1, 2
D
None
Question 10 Explanation: 
When light travels from a denser medium into a rarer medium, the refracted ray is bent away from the normal drawn to the interface. When light travels from a rarer medium into a denser medium, the refracted ray is bent towards the normal drawn to the interface.
Question 11
  • Assertion(A): Sun is the fundamental and natural source of light
  • Reason(R): It is a monochromatic source of light
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is Correct and (R) is wrong
Question 11 Explanation: 
We know that Sun is the fundamental and natural source of light. If a source of light produces a light of single colour, it is known as a monochromatic source.
Question 12
Which of the following is an example of composite source of light?
  1. Sun
  2. Sodium vapour lamp
  3. Mercury vapour lamp
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 12 Explanation: 
A composite source of light produces a white light which contains light of different colours. Sun light is a composite light which consists of light of various colours or wavelengths. Another example for a composite source is a mercury vapour lamp.
Question 13
Which of the following statement is correct?
  1. When a beam of white light is refracted through any transparent media such as glass it is split into its component colours
  2. This phenomenon is called as ‘dispersion of light’.
A
1 alone
B
2 alone
C
1, 2
D
None
Question 13 Explanation: 
When a beam of white light or composite light is refracted through any transparent media such as glass or water, it is split into its component colours. This phenomenon is called as ‘dispersion of light’. The band of colours is termed as spectrum.
Question 14
Arrange the spectrum of colours in order
  1. Indigo
  2. Yellow
  3. Red
  4. Violet
A
1, 3, 2, 4
B
4, 1, 2, 3
C
4, 1, 3, 2
D
2, 1, 3, 4
Question 14 Explanation: 
The band of colours is termed as spectrum. This spectrum consists of following colours: Violet, Indigo, Blue, Green, Yellow, Orange, and Red. These colours are represented by the acronym “VIBGYOR”.
Question 15
Why do we get the spectrum when white light is refracted by a transparent medium?
A
Bending of the light at different angles
B
Converging of light
C
Bending of light at same angle
D
All the above
Question 15 Explanation: 
We get the spectrum when white light is refracted by a transparent medium, this is because different coloured lights are bent through different angles. That is the angle of refraction is different for different colours.
Question 16
Which colour has highest angle of refraction?
A
Blue
B
Red
C
Violet
D
Orange
Question 16 Explanation: 
Angle of refraction is the smallest for red and the highest for violet. From Snell’s law, we know that the angle of refraction is determined in terms of the refractive index of the medium. Hence, the refractive index of the medium is different for different coloured lights. This indicates that the refractive index of a medium is dependent on the wavelength of the light.
Question 17
Which of the following statement is correct?
  1. When sunlight enters the Earth’s atmosphere, the atoms and molecules of different gases present in the atmosphere refract the light in all possible directions
  2. This is called as ‘Scattering of light’.
  3. The interacting particle of the medium is called as ‘scatterer’.
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 17 Explanation: 
When sunlight enters the Earth’s atmosphere, the atoms and molecules of different gases present in the atmosphere refract the light in all possible directions. This is called as ‘Scattering of light’. In this phenomenon, the beam of light is redirected in all directions when it interacts with a particle of medium. The interacting particle of the medium is called as ‘scatterer’.
Question 18
Based on initial and final energy of the light beam, scattering can be classified into_______ types
A
4
B
2
C
3
D
5
Question 18 Explanation: 
When a beam of light, interacts with a constituent particle of the medium, it undergoes many kinds of scattering. Based on initial and final energy of the light beam, scattering can be classified as, 1) Elastic scattering 2) Inelastic scattering
Question 19
Which of the following statement is correct?
  1. If the energy of the incident beam of light and the scattered beam of light are same, then it is called as ‘elastic scattering’.
  2. If the energy of the incident beam of light and the scattered beam of light are different, then it is called as ‘elastic scattering’.
A
1 alone
B
2 alone
C
1, 2
D
None
Question 19 Explanation: 
If the energy of the incident beam of light and the scattered beam of light are same, then it is called as ‘elastic scattering’.
Question 20
Nature and size of the scatterer results in_______ types of scattering
  1. Rayleigh scattering
  2. Mie scattering
  3. Raman scattering
  4. Tyndall scattering
A
1, 2, 4
B
2, 3, 4
C
1, 3, 4
D
All the above
Question 20 Explanation: 
If the energy of the incident beam of light and the scattered beam of light are not same, then it is called as ‘inelastic scattering’. The nature and size of the scatterer results in different types of scattering. They are: Rayleigh scattering Mie scattering Tyndall scattering Raman scattering
Question 21
The scattering of sunlight by the atoms or molecules of the gases in the earth’s atmosphere is____
A
Rayleigh scattering
B
Raman scattering
C
Mie scattering
D
Tyndall scattering
Question 21 Explanation: 
The scattering of sunlight by the atoms or molecules of the gases in the earth’s atmosphere is known as Rayleigh scattering.
Question 22
Which of the following expresses the Amount of scattering according to Rayleigh scattering?
A
1 /λ^4
B
1 /λ^3
C
1 /λ^2
D
1 /λ^7
Question 22 Explanation: 
Rayleigh’s scattering law states that, “The amount of scattering of light is inversely proportional to the fourth power of its wavelength”. Amount of scattering ‘S’ ∝ 1 /λ^4
Question 23
  • Assertion(A): Scattering causes the sky to appear in blue colour
  • Reason(R): When sunlight passes through the atmosphere, the blue colour (shorter wavelength)  is scattered to a greater extent than the red colour (longer wavelength).
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is Correct and (R) is wrong
Question 23 Explanation: 
According to Rayleigh’s scattering law, the shorter wavelength colours are scattered much more than the longer wavelength colours. When sunlight passes through the atmosphere, the blue colour (shorter wavelength) is scattered to a greater extent than the red colour (longer wavelength). This scattering causes the sky to appear in blue colour.
Question 24
  • Assertion(A): At sunrise and sunset, the light rays from the Sun appears red in colour
  • Reason(R): Most of the blue lights are scattered away and only the red light which gets least  scattered reaches us during morning and the evening
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is Correct and (R) is wrong
Question 24 Explanation: 
At sunrise and sunset, the light rays from the Sun have to travel a larger distance in the atmosphere than at noon. Hence, most of the blue lights are scattered away and only the red light which gets least scattered reaches us. Therefore, the colour of the Sun is red at sunrise and sunset.
Question 25
Which of the following statement is correct about Mie scattering?
  1. Mie scattering takes place when the diameter of the scatterer is similar to or larger than the wavelength of the incident light.
  2. The amount of scattering is dependents on the wave length.
  3. Mie scattering is caused by pollen, dust, smoke, water droplets, and other particles in the lower portion of the atmosphere
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 25 Explanation: 
Mie scattering takes place when the diameter of the scatterer is similar to or larger than the wavelength of the incident light. It is also an elastic scattering. The amount of scattering is independent of wave length. Mie scattering is caused by pollen, dust, smoke, water droplets, and other particles in the lower portion of the atmosphere.
Question 26
__________ is responsible for the white appearance of the cloud
A
Rayleigh scattering
B
Mie scattering
C
Tyndall scattering
D
Raman scattering
Question 26 Explanation: 
Mie scattering is responsible for the white appearance of the clouds. When white light falls on the water drop, all the colours are equally scattered which together form the white light.
Question 27
When a beam of sunlight, enters into a dusty room through a window, then its path becomes visible to us. This an example of____ effect
A
Rayleigh scattering
B
Mie scattering
C
Tyndall scattering
D
Raman scattering
Question 27 Explanation: 
When a beam of sunlight, enters into a dusty room through a window, then its path becomes visible to us. This is because, the tiny dust particles present in the air of the room scatter the beam of light. This is an example of Tyndall Scattering.
Question 28
Tyndall Effect takes place in______ solution
A
Colloidal
B
True
C
Suspension
D
All the above
Question 28 Explanation: 
The scattering of light rays by the colloidal particles in the colloidal solution is called Tyndall Scattering or Tyndall Effect. Colloid is a microscopically small substance that is equally dispersed throughout another material. Example: Milk, Ice cream, muddy water, smoke.
Question 29
Which scattering speaks about additional frequencies in the scattering the monochromatic light?
A
Rayleigh scattering
B
Mie scattering
C
Tyndall scattering
D
Raman scattering
Question 29 Explanation: 
When a parallel beam of monochromatic (single coloured) light passes through a gas or liquid or transparent solid, a part of light rays is scattered. The scattered light contains some additional frequencies (or wavelengths) other than that of incident frequency (or wavelength). This is known as Raman scattering or Raman Effect.
Question 30
The spectral lines having frequency equal to the incident ray frequency is_____
A
Normal line
B
Rayleigh line
C
Incident line
D
None
Question 30 Explanation: 
Raman Scattering is defined as “The interaction of light ray with the particles of pure liquids or transparent solids, which leads to a change in wavelength or frequency.” The spectral lines having frequency equal to the incident ray frequency is called ‘Rayleigh line’ and the spectral lines which are having frequencies other than the incident ray frequency are called ‘Raman lines’.
Question 31
The lines having frequencies higher than the incident frequency are called as_____
A
Stoke lines
B
Anti-stoke lines
C
Refracted lines
D
All the above
Question 31 Explanation: 
The lines having frequencies lower than the incident frequency is called stokes lines and the lines having frequencies higher than the incident frequency are called Anti-stokes lines.
Question 32
How many spherical refracting surfaces are there in lenses?
A
1
B
4
C
3
D
2
Question 32 Explanation: 
A lens is an optically transparent medium bounded by two spherical refracting surfaces or one plane and one spherical surface.
Question 33
Which of the following are the features of Convex lens?
  1. It is a lens bounded by two spherical surfaces such that it is thicker at the centre than at the edges
  2. A convex lens is also called as converging lens
  3. A beam of light passing through it, is converged to a point
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 33 Explanation: 
Convex or bi-convex lens is a lens bounded by two spherical surfaces such that it is thicker at the centre than at the edges. A beam of light passing through it, is converged to a point. So, a convex lens is also called as converging lens.
Question 34
Which of the following statement is correct about Concave or bi-concave Lens?
  1. It is a lens bounded by two spherical surfaces such that it is thinner at the centre than at the edges
  2. A parallel beam of light passing through it will spread in
  3. A concave lens is also called as diverging lens.
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 34 Explanation: 
Concave or bi-concave Lens is a lens bounded by two spherical surfaces such that it is thinner at the centre than at the edges. A parallel beam of light passing through it, is diverged or spread out. So, a concave lens is also called as diverging lens.
Question 35
If one of the faces of a bi-convex lens is plane, it is known as a_______
A
Plano-concave lens
B
Convex mirror
C
Plano-convex lens
D
None
Question 35 Explanation: 
Plano-convex lens: If one of the faces of a bi-convex lens is plane, it is known as a planoconvex lens. Plano-concave lens: If one of the faces of a bi-concave lens is plane, it is known as a planoconcave lens
Question 36
Which of the following shows the features of image formed?
  1. Position
  2. Size
  3. Nature of the image
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 36 Explanation: 
When an object is placed in front of a lens, the light rays from the object fall on the lens. The position, size and nature of the image formed can be understood only if we know certain basic rules.
Question 37
Match the following with
  1. Ray of light strikes at the optical centre                 1. refracted ray will be parallel to the   principal axis
  2. Ray of light parallel to principal axis                  2. it continues to follow its path without  any deviation
  3. Ray of light strikes directed towards                        3.  Either converge or diverge from principal  the principal focus                                                                     axis based on type of lens
A
3, 1, 2
B
2, 3, 1
C
1, 3, 2
D
2, 1, 3
Question 37 Explanation: 
Rule-1: When a ray of light strikes the convex or concave lens obliquely at its optical centre, it continues to follow its path without any deviation Rule-2: When rays parallel to the principal axis strikes a convex or concave lens, the refracted rays are converged to (convex lens) or appear to diverge from (concave lens) the principal focus Rule-3: When a ray passing through (convex lens) or directed towards (concave lens) the principal focus strikes a convex or concave lens, the refracted ray will be parallel to the principal axis
Question 38
What will be the size of the image in convex lens in case of Object at infinity?
A
Size of the image is much smaller than that of the object
B
Size of the image is equal to that of the object
C
Size of the image is much larger than that of the object
D
None
Question 38 Explanation: 
Let us discuss the formation of images by a convex lens when the object is placed at various positions. When an object is placed at infinity, a real image is formed at the principal focus. The size of the image is much smaller than that of the object.
Question 39
Match the following with the position of image formation in the case of convex lens
  1. Object placed beyond C                                        1. real image is formed at infinity
  2. Object placed at C                                              2. real and inverted image is formed behind                                                                                          the centre of curvature
  3. Object placed between F and C                                3. image is formed between the centre                                                                                              of curvature and the principal focus
  4. Object placed at the principal focus F                       4. a real and inverted image is formed                                                                                             at   the  other centre of curvature
A
1, 2, 4, 3
B
3, 4, 2, 1
C
3, 2, 1, 4
D
2, 1, 4, 3
Question 39 Explanation: 
Object placed beyond C (>2F): When an object is placed behind the centre of curvature (beyond C), a real and inverted image is formed between the centre of curvature and the principal focus. Th e size of the image is the same as that of the object Object placed at C: When an object is placed at the centre of curvature, a real and inverted image is formed at the other centre of curvature. The size of the image is the same as that of the object. Object placed between F and C: When an object is placed in between the centre of curvature and principal focus, a real and inverted image is formed behind the centre of curvature. The size of the image is bigger than that of the object Object placed at the principal focus F: When an object is placed at the focus, a real image is formed at infinity. The size of the image is much larger than that of the object Object placed between the principal focus F and optical centre O: When an object is placed in between principal focus and optical centre, a virtual image is formed. The size of the image is larger than that of the object
Question 40
Which of the following are the uses of Convex lenses?
  1. Convex lenses are used as magnifying lenses
  2. They are used as camera lenses
  3. They are used to correct the defect of vision called myopia
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 40 Explanation: 
APPLICATIONS OF CONVEX LENSES: Convex lenses are used as camera lenses They are used as magnifying lenses They are used in making microscope, telescope and slide projectors They are used to correct the defect of vision called hypermetropia
Question 41
Which of the following statement about concave lens is incorrect?
  1. When an object is placed at infinity, a virtual image is formed at the focus
  2. When an object is placed at a finite distance from the lens, a virtual image is formed between optical centre and focus of the concave lens
A
1 alone
B
2 alone
C
1, 2
D
None
Question 41 Explanation: 
When an object is placed at infinity, a virtual image is formed at the focus. The size of the image is much smaller than that of the object. When an object is placed at a finite distance from the lens, a virtual image is formed between optical centre and focus of the concave lens. The size of the image is smaller than that of the object.
Question 42
What happens the distance between the object and the lens is decreased in a Concave lens?
A
The distance between the image and the lens also keeps decreases
B
The distance between the image and the lens also keeps increases
C
The distance between the image and the lens will be same
D
None
Question 42 Explanation: 
In a concave lens, as the distance between the object and the lens is decreased, the distance between the image and the lens also keeps decreasing. Further, the size of the image formed increases as the distance between the object and the lens is decreased.
Question 43
Which of the following are the uses of concave lens?
  1. Concave lenses are used as eye lens of ‘Galilean Telescope’
  2. They are used in wide angle spy hole in doors
  3. They are used to correct the defect of vision called ‘myopia’
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 43 Explanation: 
APPLICATIONS OF CONCAVE LENSES: Concave lenses are used as eye lens of ‘Galilean Telescope’ They are used in wide angle spy hole in doors. They are used to correct the defect of vision called ‘myopia’
Question 44
Which of the following gives the focal length (f) of the lens?
A
u + v
B
u – v
C
1/u – 1/v
D
1/u + 1/v
Question 44 Explanation: 
Like spherical mirrors, we have lens formula for spherical lenses. The lens formula gives the relationship among distance of the object (u), distance of the image (v) and the focal length (f) of the lens. It is expressed as: 1/f = 1/u – 1/v It is applicable to both convex and concave lenses. We need to give an at most care while solving numerical problems related to lenses in taking proper signs of different quantities.
Question 45
Which of the following statement about Cartesian sign conventions are correct?
  1. The object is always placed on the left side of the lens.
  2. The distances measured upward and perpendicular to the principal axis is taken as positive
  3. The distances measured in the same direction as that of incident light are taken as positive.
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 45 Explanation: 
spherical lenses. According to cartesian sign convention, The object is always placed on the left side of the lens. All the distances are measured from the optical centre of the lens. The distances measured in the same direction as that of incident light are taken as positive. The distances measured against the direction of incident light are taken as negative. The distances measured upward and perpendicular to the principal axis is taken as positive. The distances measured downward and perpendicular to the principal axis is taken as negative.
Question 46
Which of the following signifies the Magnification of lens?
A
height of the image/ height of the object
B
height of the image X height of the object
C
height of the image + height of the object
D
height of the image - height of the object
Question 46 Explanation: 
Like spherical mirrors, we have magnification for spherical lenses. Spherical lenses produce magnification and it is defined as the ratio of the height of the image to the height of an object. Magnification is denoted by the letter ‘m’. If height of the object is h and height of the image is h´, the magnification produced by lens is, m = height of the image /height of the object = h' /h
Question 47
If magnification is greater than 1, then we get a/an_____ image
A
Same size
B
Enlarged
C
Diminished
D
None
Question 47 Explanation: 
If the magnification is greater than 1, then we get an enlarged image. On the other hand, if the magnification is less than 1, then we get a diminished image.
Question 48
Which of the following statement about lens is correct?
  1. All lenses are made up of transparent materials
  2. Any optically transparent material will have a refractive index
  3. The lens formula relates the focal length of a lens with the distance of object and image.
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 48 Explanation: 
All lenses are made up of transparent materials. Any optically transparent material will have a refractive index. The lens formula relates the focal length of a lens with the distance of object and image. For a maker of any lens, knowledge of radii of curvature of the lens is required. This clearly indicates the need for an equation relating the radii of curvature of the lens, the refractive index of the given material of the lens and the required focal length of the lens.
Question 49
The ability to converge or diverge these light rays depends on______ of the lens
A
Principal axis
B
Focal length
C
Refractive index
D
None
Question 49 Explanation: 
It is clear that when a ray of light falls on a lens, the ability to converge or diverge these light rays depends on the focal length of the lens.
Question 50
What is the formula to calculate the Power of a lens?
A
1 /f
B
– f
C
u – v
D
f/x
Question 50 Explanation: 
The ability of a lens to converge (convex lens) or diverge (concave lens) is called as its power. Hence, the power of a lens can be defined as the degree of convergence or divergence of light rays. Power of a lens is numerically defined as the reciprocal of its focal length. P = 1 /f
Question 51
What is the SI unit of Power of a lens?
A
Dioptre
B
m
C
1/m
D
1/D
Question 51 Explanation: 
The SI unit of power of a lens is dioptre. It is represented by the symbol D. If focal length is expressed in ‘m’, then the power of lens is expressed in ‘D’. Thus, 1D is the power of a lens, whose focal length is 1metre. 1D = 1m^-1
Question 52
What is the power of concave lens?
A
Positive
B
Negative
C
Neutral
D
None
Question 52 Explanation: 
By convention, the power of a convex lens is taken as positive whereas the power of a concave lens is taken, as negative. The lens formula and lens maker’s formula are applicable to only thin lenses. In the case of thick lenses, these formulae with little modifications are used.
Question 53
What is the diameter of eye ball?
A
2.3 cm
B
2.3 m
C
12.3 cm
D
1.3 m
Question 53 Explanation: 
The eye ball is approximately spherical in shape with a diameter of about 2.3 cm. It consists of a tough membrane called sclera, which protects the internal parts of the eye.
Question 54
Which of the following refracts or bends the light on to the lens?
A
Cornea
B
Pupil
C
Retina
D
All the above
Question 54 Explanation: 
Cornea is the thin and transparent layer on the front surface of the eyeball. It is the main refracting surface. When light enters through the cornea, it refracts or bends the light on to the lens.
Question 55
_____ is the back surface of the eye
A
Pupil
B
Retina
C
Ciliary muscles
D
All the above
Question 55 Explanation: 
Retina is the back surface of the eye. It is the most sensitive part of human eye, on which real and inverted image of objects is formed.
Question 56
Which of the following are the possible colours of the Iris?
  1. Red
  2. Blue
  3. Green
  4. Brown
A
1, 2, 4
B
2, 3, 4
C
1, 3, 4
D
All the above
Question 56 Explanation: 
Iris is the coloured part of the eye. It may be blue, brown or green in colour. Every person has a unique colour, pattern and texture. Iris controls amount of light entering into the pupil like camera aperture.
Question 57
Eye lens is fixed between_______
  1. Pupil
  2. Retina
  3. Ciliary muscles
A
1, 2
B
1, 3
C
3 alone
D
All the above
Question 57 Explanation: 
Eye lens is fixed between the ciliary muscles. It helps to change the focal length of the eye lens according to the position of the object.
Question 58
Human eye is in nature?
A
Concave
B
Convex
C
a or b
D
None
Question 58 Explanation: 
Pupil is the centre part of the Iris. It is the pathway for the light to retina. Eye Lens is the important part of human eye. It is convex in nature.
Question 59
Which of the following statement is correct?
  1. The transparent layer cornea bends the light rays through pupil located at the centre part of the Iris.
  2. The adjusted light passes through the eye lens
  3. Retina passes the received real and inverted image to the brain through optical nerves
A
1, 2
B
1, 3
C
3 alone
D
All the above
Question 59 Explanation: 
The transparent layer cornea bends the light rays through pupil located at the centre part of the Iris. The adjusted light passes through the eye lens. Eye lens is convex in nature. So, the light rays from the objects are converged and a real and inverted image is formed on retina. Then, retina passes the received real and inverted image to the brain through optical nerves. Finally, the brain senses it as erect image.
Question 60
  • Assertion(A): The ability of the eye lens to focus nearby as well as the distant objects is called  power of accommodation of the eye
  • Reason(R): This is achieved by changing the focal length of the eye lens with the help of ciliary  muscles.
A
Both (A) and (R) are correct, but (R) does not explain (A)
B
Both (A) and (R) are wrong
C
Both (A) and (R) are correct and (R) explains (A)
D
(A) is Correct and (R) is wrong
Question 60 Explanation: 
The ability of the eye lens to focus nearby as well as the distant objects is called power of accommodation of the eye. This is achieved by changing the focal length of the eye lens with the help of ciliary muscles.
Question 61
Which of the following statement is correct?
  1. Eye lens is made of a flexible, jelly-like material
  2. When we see distant objects, the ciliary muscle relaxes and makes the eye lens thinner
  3. when we look at a closer object, the focal length of the eye lens is decreased by the contraction of ciliary muscle
A
1, 2
B
1, 3
C
3 alone
D
All the above
Question 61 Explanation: 
Eye lens is made of a flexible, jelly-like material. By relaxing and contracting the ciliary muscle, the curvature and hence the focal length of the eye lens can be altered. When we see distant objects, the ciliary muscle relaxes and makes the eye lens thinner. This increases the focal length of the eye lens. Hence, the distant object can be clearly seen. On the other hand, when we look at a closer object, the focal length of the eye lens is decreased by the contraction of ciliary muscle. Thus, the image of the closer object is clearly formed on the retina.
Question 62
What is the minimum time required by the eye to distinguish consecutive light pulses?
A
1 sec
B
0.1 sec
C
10 sec
D
1 msec
Question 62 Explanation: 
If the time interval between two consecutive light pulses is less than 0.1 second, human eye cannot distinguish them separately. It is called persistence of vision.
Question 63
What is the minimum distance required by human eye to see the objects distinctly without strain?
A
25 m
B
25 cm
C
15 cm
D
15 m
Question 63 Explanation: 
The minimum distance required to see the objects distinctly without strain is called least distance of distinct vision. It is called as near point of eye. It is 25 cm for normal human eye.
Question 64
What is the far point of the eye?
A
150 m
B
100 m
C
200 m
D
Infinity
Question 64 Explanation: 
The maximum distance up to which the eye can see objects clearly is called as far point of the eye. It is infinity for normal eye.
Question 65
Which of the following statement is correct?
  1. A normal human eye can clearly see all the objects placed between 25cm and infinity
  2. But, for some people, the eye loses its power of accommodation.
A
1 alone
B
2 alone
C
1, 2
D
None
Question 65 Explanation: 
A normal human eye can clearly see all the objects placed between 25cm and infinity. But, for some people, the eye loses its power of accommodation. Th is could happen due to many reasons including ageing. Hence, their vision becomes defective.
Question 66
Which of the following statement about myopia is correct?
  1. Myopia, also known as short sightedness
  2. It occurs due to the shortening of eye ball
  3. The focal length of eye lens is reduced or the distance between eye lens and retina increases
A
1, 2
B
1, 3
C
3 alone
D
All the above
Question 66 Explanation: 
Myopia, also known as short sightedness, occurs due to the lengthening of eye ball. With this defect, nearby objects can be seen clearly but distant objects cannot be seen clearly. Th e focal length of eye lens is reduced or the distance between eye lens and retina increases. Hence, the far point will not be infinity for such eyes and the far point has come closer.
Question 67
Myopia can be corrected with_____
A
Concave lens
B
Convex lens
C
Bi-focal lens
D
None
Question 67 Explanation: 
In the case of myopia, image of distant objects is/are formed before the retina. This defect can be corrected using a concave lens.
Question 68
What is the formula to calculate the focal length of concave lens in the case of myopia?
A
x y /x−y
B
x /x−y
C
y /x−y
D
x−y / x y
Question 68 Explanation: 
Let a person with myopia eye can see up to a distance x. Suppose that he wants to see all objects farther than this distance, i.e., up to infinity. Then the focal length of the required concave lens is f = –x. If the person can see up to a distance x and he wants to see up to a distance y, then, the focal length of the required concave lens is, f = x y /x – y
Question 69
Which of the following statement is correct about Hypermetropia?
  1. Hypermetropia, also known as long sightedness
  2. It occurs due to the shortening of eye ball
  3. Th e focal length of eye lens is increased or the distance between eye lens and retina decreases.
A
1, 2
B
1, 3
C
3 alone
D
All the above
Question 69 Explanation: 
Hypermetropia, also known as long sightedness, occurs due to the shortening of eye ball. With this defect, distant objects can be seen clearly but nearby objects cannot be seen clearly. The focal length of eye lens is increased or the distance between eye lens and retina decreases. Hence, the near point will not be at 25cm for such eyes and the near point has moved farther. Due to this, the image of nearby objects is/are formed behind the retina. This defect can be corrected using a convex lens.
Question 70
Which of the following statement is incorrect?
  1. Due to ageing, ciliary muscles become weak and the eye-lens become rigid (inflexible) and so the eye loses its power of accommodation.
  2. Presbyopia is also called as ‘old age hypermetropia’
A
1 alone
B
2 alone
C
1, 2
D
None
Question 70 Explanation: 
Due to ageing, ciliary muscles become weak and the eye-lens become rigid (inflexible) and so the eye loses its power of accommodation. Because of this, an aged person cannot see the nearby objects clearly. So, it is also called as ‘old age hypermetropia’.
Question 71
Presbyopia can be corrected with______ lens
A
Concave
B
Convex
C
Bifocal
D
It cannot be corrected
Question 71 Explanation: 
Some persons may have both the defects of vision - myopia as well as hypermetropia. This can be corrected by bifocal lenses. In which, upper part consists of concave lens (to correct myopia) used for distant vision and the lower part consists of convex lens (to correct hypermetropia) used for reading purposes.
Question 72
Astigmatism can be corrected by using________ lenses
A
Concave
B
Convex
C
Bifocal
D
Cylindrical
Question 72 Explanation: 
In this defect, eye cannot see parallel and horizontal lines clearly. It may be inherited or acquired. It is due to the imperfect structure of eye lens because of the development of cataract on the lens, ulceration of cornea, injury to the refracting surfaces, etc. Astigmatism can be corrected by using cylindrical lenses (Torrid lenses).
Question 73
Simple microscope has a ______lens of short focal length
A
Concave
B
Convex
C
Bifocal
D
Cylindrical
Question 73 Explanation: 
Microscope works under the principle of angular magnification of lenses. It is classified as Simple microscope Compound microscope Simple microscope has a convex lens of short focal length. It is held near the eye to get enlarged image of small objects.
Question 74
Which of the following are the uses of Simple microscope?
  1. watch repairers and jewellers
  2. observe parts of flower, insects etc
  3. to observe finger prints in the field of forensic science.
A
1, 2
B
1, 3
C
3 alone
D
All the above
Question 74 Explanation: 
Simple microscopes are used by watch repairers and jewellers. to read small letters clearly. to observe parts of flower, insects etc. to observe finger prints in the field of forensic science
Question 75
Which of the following statement is correct?
  1. Compound microscope is also used to see the tiny objects.
  2. It has better magnification power than simple microscope.
  3. Magnification power of microscopes can be increased by decreasing the focal length of the lens used
A
1, 2
B
1, 3
C
3 alone
D
All the above
Question 75 Explanation: 
Compound microscope is also used to see the tiny objects. It has better magnification power than simple microscope. Magnification power of microscopes can be increased by decreasing the focal length of the lens used. Due to constructional limitations, the focal length of the lens cannot be decreased beyond certain limit. This problem can be solved by using two separate biconvex lenses.
Question 76
How many lenses are there in a compound microscope?
A
4
B
2
C
3
D
1
Question 76 Explanation: 
A compound microscope consists of two convex lenses. The lens with the shorter focal length is placed near the object, and is called as ‘objective lens’ or ‘objective piece’. The lens with larger focal length and larger aperture placed near the observer’s eye is called as ‘eye lens’ or ‘eye piece’. Both the lenses are fixed in a narrow tube with adjustable provision.
Question 77
How many times more magnification power than simple microscope than compound microscope  does have?
A
5 to 10
B
50 to 100
C
50 to 200
D
100 to 200
Question 77 Explanation: 
Compound microscope has 50 to 200 times more magnification power than simple microscope. A travelling microscope is one of the best instruments for measuring very small length with high degree of accuracy at the order of 0.01mm. It works based on the principle of vernier. Its least count is 0.01 mm.
Question 78
The first telescope was invented by_________
A
Newton
B
Galileo
C
Jan Lippershey
D
Einstein
Question 78 Explanation: 
Telescope is an optical instrument to see the distant objects. The first telescope was invented by Jan Lippershey in 1608. Galileo made a telescope to observe distant stars. He got the idea, from a spectacle maker who one day observed that the distant weather cock appeared magnified through his lens system fitted in his shop.
Question 79
Who invented a telescope which was fundamentally similar to the astronomical telescope?
A
Newton
B
Galileo
C
Jan Lippershey
D
Kepler
Question 79 Explanation: 
Galileo observed the satellites of Jupiter and the rings of Saturn through his telescope. Kepler invented Telescope in 1611 which was fundamentally similar to the astronomical telescope.
Question 80
According to optical property, telescopes are classified into___ types
A
3
B
4
C
2
D
5
Question 80 Explanation: 
According to optical property, it is classified into two groups: refracting telescope reflecting telescope In refracting telescope lenses are used. Galilean telescope, Keplerian telescope, Achromatic refractors, Apochromatic refractors are some refracting telescopes. In reflecting telescope parabolic mirrors are used Gregorian, Newtonian, Cassegrain telescope, Ritchey–Chrétien telescope are some Reflecting telescopes According to the things which are observed, Astronomical Telescope and Terrestrial Telescopes are the two major types of telescope
Question 81
Which of the following statement is correct?
  1. The image in an astronomical telescope is real
  2. It is not suitable for viewing objects on the surface of the Earth
  3. The major difference between astronomical and terrestrial telescope is erecting the final image with respect to the object
A
1, 2
B
1, 3
C
2, 3
D
All the above
Question 81 Explanation: 
The image in an astronomical telescope is inverted. So, it is not suitable for viewing objects on the surface of the Earth. Therefore, a terrestrial telescope is used. It provides an erect image. The major difference between astronomical and terrestrial telescope is erecting the final image with respect to the object.
Question 82
A person with myopia can see objects placed at a distance of 4m. If he wants to see objects at a distance of 20m, what should be the power of the concave lens he must wear?
A
0.2 D
B
– 0.2 D
C
0.5 D
D
– 0.5 D
Question 83
A beam of light passing through a diverging lens of focal length 0.3m appear to be focused at a distance 0.2m behind the lens. Find the position of the object.
A
−0.6 m
B
0.6 m
C
0.3 m
D
– 0.3 m
Question 84
For a person with hypermetropia, the near point has moved to 1.5m. Calculate the focal length of  the correction lens in order to make his eyes normal.
A
0.3 m
B
0.6 m
C
- 0.5 m
D
– 0.6 m
Once you are finished, click the button below. Any items you have not completed will be marked incorrect. Get Results
There are 84 questions to complete.

Leave a Reply

Your email address will not be published. Required fields are marked *