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Worksheetsoptics
Total questions: 70
Worksheet time: 45mins
What type of interference is represented in this diagram?
Constructive
Destructive
What type of interference do noise cancelling headphones use?
Constructive Interference
Destructive Interference
True or False? Two waves cannot exist in the same space or in the same medium at the same time.
True
False
Through which material does sound travel slowest?
Water
Paper
Aluminum
Air
None of the above
A diffraction grating is used to measure the wavelength of monochromatic light, as shown in the diagram.
The spacing of the slits in the grating is 1.00 x10-6 m. The angle between the first order diffraction maxima is 70.0o.
What is the wavelength of the light?
287 nm
470 nm
574 nm
940 nm
Interference of light is evidence that:
the speed of light is very large
light is a transverse wave
light is electromagnetic in character
light is a wave phenomenon
In a Young's double-slit experiment the centre of a bright fringe occurs wherever waves from the slits differ in the distance they travel by a multiple of:
quarter of a wavelength.
half a wavelength.
a wavelength.
three-fourths of a wavelength.
In a Young's double-slit experiment, the slit separation is doubled. To maintain the same fringe spacing on the screen, the screen-to-slit distance D must be changed to:
D/2
D 2
2D
4D
Extra distance travelled by one of waves compared with other is called
path.
displacement.
phase difference.
path difference.
What principle is responsible for light spreading as it passes through a narrow slit?
refraction
polarization
diffraction
interference
Two light sources are said to be coherent if they
are of the same frequency.
are of the same frequency, and maintain a constant phase difference.
are of the same amplitude, and maintain a constant phase difference.
are of the same frequency and amplitude.
It is shone through a double slit spacing 0.2mm onto a screen 2m away.
The fringe spacing is?
How many diffraction maxima will be seen in total
A wave of constant wavelength diffracts as it passes through an opening in a barrier. As the size of the opening is increased, the diffraction effects
decrease
increase
remain the same
What would you call this?
Reflection
Diffraction
Refraction
Friction
In, Fresnel type of diffraction
Source at finite distance and screen at infinite distance
Source and screen are at infinite distance
Source at infinite distance and screen at finite distance
Both source and screen are at a finite distance
In Fraunhofer class of diffraction
The source and screen are at infinite distance
The source is at finite distance and screen is at infinite distance
The source and screen are at a finite distance
The source is at infinite distance and screen is at a finite distance
In which type of diffraction, diffracted light is collected by a lens in a telescope
Fresnel's
Fraunhoffer's
Both
None
In single slit Fraunhoffer diffraction, the position of minima is given by
θ=0
a sinθ=±mλ where m=1, 2,3....
asinθ=± 2(2m+1)λ
The resolving power of a grating decreases with the increase in the number of lines on grating.
True
False
Each slit has a width of 0.15 mm and the distance between their center is 0.75 mm. What are the missing spectra.
3, 6, 9,..... order will be missing.
2, 4, 6,..... order will be missing.
5,10, 15,..... order will be missing.
4,8, 12,..... order will be missing.
What should be the thickness of quarter wave plate for a light of wavelength 5000 Å if µe=1.553 and µo=1.544
1.38x10-3 cm
1.43x10-3 cm
1.53x10-3 cm
1.63x10-3 cm
The velocity of light in water is 1.5x108 m/s. What is the polarizing angle of incidence.
47.230
51.030
53.740
63.430
Which of the phenomena suggests that light may be a transverse wave?
Interference
Diffraction
Reflection
Polarization
What happen if o-ray and e-ray travel along the optic axis?
Both rays travel with the same speed.
o-ray travel faster than e-ray.
e-ray travel faster than o-ray.
none of these
How much phase change is introduced by a quarter wave plate between ordinary and extraordinary rays ?
2π
π
4π
0
The plane in which electric field vector of plane polarised light vibrates is known as
Plane of vibration
Plane of polarisation
Principle plane
none of these
Properties of waves are
I. polarization
II. diffraction
III. refraction
Which of these properties apply to sound waves?
I and II
II and III
I and III
All of them
Approximately how much light is blocked by two polarizing filters that are perpendicular to each other?
0%
50%
75%
100%
? If the polarizing axis of the second filter is parallel to
that of the first, the light will .............
pass through it
block
reflect
Which of the following statements are true?
- LASER is used as optical source in single mode fibers.
- LASER lights are highly incoherent.
1. is true and 2. is false
1. is false and 2. is true
Both 1 & 2 are true
Both 1 & 2 are false
Naturally occuring process in a LASER is
Stimulated Emission
Absorption
Spontaneous Emission
Population Inversion
The process in which the electrons in the ground state are vibrated to the excited states by providing extra energy from energy sources is called as
Population Inversion
Spontaneous emission
Stimulated emission
Pumping
The coherent nature of light from LASER is due to
Spontaneous emission
Stimulated Emission
Absorption
Pumping
Light amplification in LASER is achieved by
Population inversion
Stimulated emission
Spontaneous emission
Pumping
The lifetime of electrons are more in
Pump state
Excited state
Meta stable state
Ground state
In a LASER diode,the light output is taken from
P-layer
Active layer
N-layer
Mirror polished reflecting surface
High optical gain in LASER diode is due to
Heavily doped P-layer
Heavily doped N-layer
Active layer
Reflective surfaces
Pumping technique employed in gas laser is
Optical pumping
Electrical Discharge Method
Direct conversion
Chemical reaction
Albert Einstein discovered the most important process of the laser. What is it?
Einstein Process
photon emission
medium process
stimulated emission
Pump system needs to raise the atoms from...
exited state to ground state
ground state to exited state
ground state to unexcited state
excited state to exited state
The medium in which atoms are excited called...
amplifying
gain
increasing
magnifying
Example for direct band gap semiconductors are
GaAs
Ge
Si
AlSb
Direct band semiconductors are used to make
Diode
Transisters
LED, Laser diodes
Integrated circuits
Active medium in semiconductor laser is
CO2
P-N junction diode
Helium
Neon
To start the stimulated emissions in direct bandgap semiconductors is required
low current density
large divergence
coherence
Large current density
--------- is an injection laser.
He-Ne laser
Semiconductor laser
Molecular gas laser
Solid state laser
Pumping technique employed in semiconductor laser is -----------
Direct conversion
Optical pumping
Electrical discharge method
Chemicla reaction
When a beam of light enters one medium from another, which quantity will not change?
Direction
Speed
Frequency
Wavelength
Laser light is ______ emission.
Coherent
Stimulated
Spontaneous
Coherent and stimulated
Coherence of laser light is important for _________
Light propagation
Getting laser light to pass through air
Drilling holes
Holography
Single mode fiber is
one mode
two mode
more than one mode
none
Step index multi mode fiber has
core diameter has 50 to 200 µm
core diameter has 100 to 200 µm
core diameter has 50 to 100 µm
core diameter has 50 to 150 µm
The core of the optical fibre is
opaque and conducting material.
opaque and dielectric material.
transparent and conducting material.
transparent and dielectric material.
A measurement of the ability of an optical fibre to capture light is called
acceptance angle.
cladding.
numerical aperature.
critical angle.
The unit of Numerical aperature is
meter
degree
Coulomb per meter
no unit.
Which of the following statement is correct?
Refractive index of core and cladding are equal.
Refractive index of core is more then that of cladding.
Refractive index of core is less then that of cladding.
Refractive index of core is less or equal to that of cladding.
If the numerical aperature of an optical fibre is 0.515, then the maximum angle of incidence is __________ degree.
0.008
17.5
31
67
The refractive index of core and cladding for a step index fibre are 1.42 and 1.29 respectively. The numerical aperature of the fibre is
0.3523
0.59
0.13
2.71
Which of the following is ( are) correct?
The refractive index of the core of the step index fiber is constant throughout the core.
The refractive index of the graded index fibre is maximum at the centre of the core and then it decreases towards core-cladding interface.
The bandwidth in fibre optical communication is very high as against in case of coaxial cable transmission.
All the above
The function of cladding is
to produce refraction of rays.
to produce total internal reflections of rays.
to produce transmission of Ray's.
to provide a firm support to the core glass.
Which cable sends data as light?
Copper
Fibre Optic
Ethernet
when we look through rainbow glasses... (diffraction-slits)... which color is bent the least (shows up closest to the object)
red
violet
yellow
green
What is the process responsible for producing photons in diode laser?
Fermi level shift
Majority carrier injection
Carrier freeze out
Electron-hole recombination
