1 |
According to Huygen's principle: |
Light travel in straight line
Light is a transvers wave
Light has dual nature
All point on the primary wavefront are the sources of secondary wavelets
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2 |
The cause of mirage observed in deserts in bright sunlight is due to: |
Refraction of light
Reflection of light
Scattering of light
Total internal reflection of light
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3 |
The velocity of light in vacuum can be changed by changing: |
Frequency
Amplitude
Wavelength
None of these
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4 |
The image of the tip of a needle is never sharp because of |
Polarization of light
Interference of light
Diffraction of light
Reflection of light
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5 |
Which one the following gives three regions of electromagnetic sepctrum in order of increasing wavelength? |
Gamma rays, micro waves, visible light
Radio waves, ultraviolet waves, X-rays
Ultraviolet rays, Infrared rays, micro waves
Visible light, gamma rays, radio waves
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6 |
Huygen's theory cannot explain: |
Diffraction
Interference
Polarization
Photoelectric effect
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7 |
The contrast in the fringes in an interference pattern depends upon |
Fringe width
Relative intensities of the two sources
Distance between the slits
Wavelength
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8 |
If yellow light emitted by sodium lamp in Young's double slit experiment is replaced by blue light of the same intensity: |
Fringe width will decrease
Fringe width will increase
Fringe width will remain unchanged
Fringe will become less intense
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9 |
Which one of the following phenomenon cannot be explained on the bases of Huygen's theory? |
Refraction
Reflection
Diffraction
Formation of spectrum
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10 |
Light appears to travel in straight line because |
It is not absorbed by the atmosphere
It is refracted by the atmosphere
Its wavelength is very small
Its velocity is very large
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11 |
Star twinkle due to |
The fact that they do not emit light continously
The refractive index of earth's atmosphere fluntuates
The star's atmosphere absorbs its light intermittently
None of these
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12 |
A prism splits a beam of white light into seven component colors. This is so because |
Phase of different colors is different
Amplitude of different colors is different
Energy of different colors is different
Velocity of different colors is different
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13 |
The re conversion of light signals into electrical signals takes place due to |
Transmitter
Receiver
Generator
None of these
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14 |
The conversion of electrical signals into light signals taken place due to |
Generator
Transmitter
Receiver
None of these
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15 |
In digital modulation, the LED or laser flashed on and off at a |
Fast rate
Very fast rate
Extremely fast rate
None of these
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16 |
Using a graded index fibres the time difference is reduced to about |
0.5 ns per km
1.0 ns per km
2.0 ns per km
2.3 ns per km
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17 |
Inspite of different dispersion, all the wavelengths arrive at the other end of the fibre at the same time. With a step-index fibre overall time difference may be about |
40 ns
30 ns
32 ns
33 ns
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18 |
The power loss can also take place due to |
Information received can be inaccurate due to dispersion
Light signal may not be perfectly monochromatic
Signal accuracy may be affected by deflective source
All of these
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19 |
Power loss taken place when a light signal travels along fibres by |
Multiple reflection
Light absorbed due to impurities in glass
At joint some light is scattered by group of atoms
All of these
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20 |
Which device converts the light signals which these amplified and decoded |
Photo cell
Photo diode
Photo transistor
None of these
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