TNPSC Physics - Optics
Exam Duration: 45 Mins Total Questions : 30
A double convex glass lens of focal length f and having a circular aperture is cut into two halves, each having a semicircular aperture.
The focal length of each half is
- (a)
f
- (b)
2f
- (c)
f/2
- (d)
infinity
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
Phenomenon of formation of three dimensional image by entrance of two light beams from laser or other coherent sources of light is called
- (a)
optical photography
- (b)
X-rays photography
- (c)
radiography
- (d)
holography
An explosion takes place on the surface of moon. An astronaut at some distance from the site of explosion will
- (a)
observe light and hear sound caused by the explosion
- (b)
observe light but not hear sound caused by the explosion
- (c)
hear sound but not observe light caused by the explosion
- (d)
neither hear sound nor observe light caused by the explosion
A light wave travelling in a transparent homogeneous medium enters another transparent homogeneous medium of higher refractive index. The speed of light in the second medium.
- (a)
is less than that in the first medium
- (b)
is more than that in the first medium
- (c)
is the same as that in the first medium
- (d)
may be more or less than that in the first medium depending on the angle of incidence
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
Assertion (A) A observer may see two rainbows one inside the other.
Reason (R) Light suffers a refraction followed by total internal reflection and then again refraction
- (a)
Both A and R is true but R is not a reason of A
- (b)
A is right but R is wrong
- (c)
Both A and R are true and R is the reason of A
- (d)
Both R and A are false
Lambert's law is related to
- (a)
reflection
- (b)
refraction
- (c)
interference
- (d)
illumination
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 }
A complete circular rainbow may be seen from
- (a)
an elevated position
- (b)
an depressed position
- (c)
height cannot be affect
- (d)
ground surface
Which one of the following is used to remove astigmatism for a human eye?
- (a)
Concave lens
- (b)
Convex lens
- (c)
Cylindrical lens
- (d)
Prismatic lens
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
Optical fibre works on the principle of
- (a)
total internal reflection
- (b)
refraction
- (c)
scattering
- (d)
interference
Suppose a rocket ship is receding from the earth at a speed of 1/10 th the velocity of light. A light in the rocket ship appears blue to the passengers on the ship.What colour would it appear to an observe on the earth?
- (a)
Blue
- (b)
Orange
- (c)
Yellow
- (d)
Yellow-orange
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
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
Rainbow is formed due to
- (a)
dispersion and focussing
- (b)
refraction and absorption
- (c)
refraction and scattering
- (d)
dispersion and total internal reflection
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
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
Total internal reflection of light is possible when light enters from
- (a)
vacuum to air
- (b)
air to glass
- (c)
water to air
- (d)
air to water
Match the following lists
List I | List II |
A.Interference of light | 1.Coherent sources |
B.Doppler's effect | 2.Change in frequency |
C.Diffraction of light | 3.Different colours of light are due to different size corpulse |
D.Corpuscular theory of light | 4.Bending of light around the corner |
- (a)
A B C D 1 2 3 4 - (b)
A B C D 1 2 4 3 - (c)
A B C D 4 3 2 1 - (d)
A B C D 2 1 3 4
Which one among the following has the highest energy?
- (a)
Blue light
- (b)
Green light
- (c)
Red light
- (d)
Yellow light
A laser beam is always
- (a)
a convergent beam
- (b)
a divergent beam
- (c)
a parallel beam
- (d)
divergent to start with and parallel later on
The image formed on the retina of a human eye is
- (a)
virtual and inverted
- (b)
virtual and erect
- (c)
real and erect
- (d)
real and inverted
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 magnifying power of a telescope can be increased by
- (a)
reducing the focal length of the eye piece
- (b)
increasing the diameter of the objective
- (c)
reducing the focal length of the objective
- (d)
increasing the diameter of the eyepiece
Cylindrical lens is used by a person suffering from
- (a)
astigmatism
- (b)
myopia
- (c)
hypermetropia
- (d)
presbyopia
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
Consider the following natural phenomena
1. Terrestrial heating
2. Reflection of light
3. Refraction of light
4. Diffraction of light
Due to which of these phenomena is mirage formed?
- (a)
1 and 2
- (b)
2, 3 and 4
- (c)
1 and 3
- (d)
Only 4
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