Physics - Optics
Exam Duration: 60 Mins Total Questions : 30
Why is red light employed for danger signals?
- (a)
Red colour is smothing to the eye
- (b)
Human eye is most sensitive to red colour
- (c)
Red light is scattered least
- (d)
Red light is scattered most
Consider the following statements
1. Compound microscope has objective lens with a very short focal length.
2. Simple microscope consists of a strong converging lens system.
3. Television camera converts the optical images into electrical video signals.
4. Hypermetropia is corrected by using a diverging lens.
Which of these statement(s) is/are correct?
- (a)
Only 4
- (b)
2 and 3
- (c)
1, 2 and 3
- (d)
1, 2, 3 and 4
Two sources of wave are called coherent, if
- (a)
both have the same amplitude of vibration
- (b)
both produce waves of the same wavelength
- (c)
both produce waves of the same wavelength having a constant phase difference
- (d)
both produce waves = having same velocity
Why does a tower appear larger and larger to a person approaching it?
1.The angle subtended by the tower at the ryrs, increases.
2. The focal length of eye lens increases.
3. The size of the image of the retina of eye increases.
Select the correct answer using the codes given above.
- (a)
Only 1
- (b)
Only 3
- (c)
1 and 3
- (d)
1, 2 and 3
The primary colours in photography are
- (a)
red, blue, yellow
- (b)
red, yellow, green
- (c)
red, blue, green
- (d)
red, green, cyan
In a simple microscope, the lens in held at a distance d from the eye and the image is formed at the least distance (D) of distinct vision from the eye. What is the magnifying power of the microscope?
- (a)
D/f
- (b)
1+ (D//d)
- (c)
(1+ D/f )
- (d)
1+ { ( D + d ) / f }
Electron microscope was invented by
- (a)
Knoll and Ernst Ruska
- (b)
Robert Koch
- (c)
Leeuwenhoek
- (d)
CPS Wanson
In which part of the eye lies the pigment, that decides the colour of the eyes of a person?
- (a)
Cornea
- (b)
Choroid
- (c)
Iris
- (d)
Vitreous body
An optician prescribes a power = -0.5 diopter. The corresponding lens must be a
- (a)
convex lens of focal length 2m
- (b)
convex lens of focal length 50cm
- (c)
concave lens of focal length 2m
- (d)
concave lens of focal length 50cm
What is viewed through an electron microscope?
- (a)
Electrons and other elementary particles
- (b)
Structure of bacteria and viruses
- (c)
Inside of human stomach
- (d)
inside of the human eye
Total internal reflection can take place when light travels from
- (a)
diamond to glass
- (b)
water to glass
- (c)
air to water
- (d)
air to glass
When a CD (compact disc used in audio and video system) is seen in sunlight. Rainbow like colours are seen. This can be explained on the basis of the phenomenon of
- (a)
reflection and diffraction
- (b)
reflection and transmission
- (c)
diffraction and transmission
- (d)
refraction, diffraction and transmission
According to the modern theory for nature of light, the light has
- (a)
particle nature only
- (b)
wave nature only
- (c)
both wave and particle ( dual nature)
- (d)
Neither particle nature nor wave nature
The amount of light reflected depends upon
- (a)
the nature of the surface
- (b)
the smoothness of the surface
- (c)
the nature of material of the object
- (d)
All of the above
When a ray or light enters a glass slab from air
- (a)
its wavelength increases
- (b)
its wavelength decreases
- (c)
its frequency increases
- (d)
Neither its wavelength nor its frequency changes
Assertion (A) Small glass beads fixed on traffic signal glow brightly when light falls upon them.
Reason (R) Light is totally reflected when the angle of incidence exceeds a certain critical value and light travelling in a denser medium is reflected from a rarer medium
- (a)
Both A and R are true and R is the correct explanation of A
- (b)
Both A and R are true but R is not a correct explanation A
- (c)
A is true but R is false
- (d)
A is false but R is true
When a ray of light is refracted by a prism such that the angle of deviation is minimum, then
- (a)
the angle of emergence is greater than angle of incidence
- (b)
the angle of emergence is equal to the angle of incidence
- (c)
the angle of emergence is smaller than the angle of incidence
- (d)
the sum of the angle of incidence and the angle of emergence is equal to 90\(^{0}\)
The spread in colours in a rainbow on sky is primarily due to
- (a)
dispersion of Sunlight
- (b)
reflection of Sunlight
- (c)
refraction of Sunlight
- (d)
total internal reflection of Sunlight
Myopia is due to
- (a)
older age
- (b)
shortening of eye ball
- (c)
elongation of eye ball
- (d)
irregular changes in the focal length of the eye lens
Consider the following statements about laws of the refraction
1.The incident ray, the refracted ray and normal to the interface at the point of incidence, all lie in the same plane.
2.Whenever light goes from one medium to another, the frequency of light do not change.However, the velocity of light and the wavelength of light change.
Which of the above statement(s) is/are correct?
- (a)
Only 2
- (b)
Only 1
- (c)
Both 1 and 2
- (d)
Neither 1 nor 2
Which of the following is not due to total internal reflection?
- (a)
Mirage on hot summer days
- (b)
Brilliance of diamond
- (c)
Difference between apparent and real depth of a pond
- (d)
Working of optical fibre
In case of hypermetropia
- (a)
a concave lens should be used for correction
- (b)
a cylindrical lens should be used for correction
- (c)
the image of a near object is formed behind the retina
- (d)
the image of distinct object is formed in front of the retina
Chromatic aberration in a lens is caused by
- (a)
interference
- (b)
diffraction
- (c)
reflection
- (d)
dispersion
Which one of the following reflects back more sunlight as compared to other three?
- (a)
Sand desert
- (b)
Paddy crop lan
- (c)
Land covered with fresh snow
- (d)
Prairie land
Which one among the following has the highest energy?
- (a)
Blue light
- (b)
Green light
- (c)
Red light
- (d)
Yellow light
A lens, immersed in a liquid becomes invisible when
- (a)
the focal length of the lens is zero
- (b)
the focal length of the lens is infinite
- (c)
the refractive index of the lens is less than the refractive index of the liquid
- (d)
the refractive index of the lens is equal to the refractive
The power of lens is - 2 D. What is its focal length?
- (a)
2 m
- (b)
1.5 m
- (c)
1.0 m
- (d)
0.5 m
Consider the following statements
1. Light waves can travel in vacuum
2. Light waves can be refracted
3. Light waves are electromagnetic
Which of the statements given above are correct?
- (a)
1, 2 and 3
- (b)
2 and 3
- (c)
1 and 3
- (d)
1 and 2
To which one of the following process is the term CMYK related?
- (a)
railway signaling
- (b)
navigation
- (c)
offset printing
- (d)
electronic voting machine
Assertion (A) A stick is dipped in water in a starting position. If observed side ways, the stick appears short and bent at the surface of water.
Reason (R) A light coming from the stick under goes scattering from water molecules giving the stick as hart and bent appearance.
- (a)
Both A and R are true and R is the correct explanation of A
- (b)
Both A and R are true but R is not a correct explanation of A
- (c)
A is true but R is false
- (d)
A is false but R is true