1 |
In a spectrometer experiment monochromatic light is incident normally on a diffraction grating having 4.5 x 105 lines per meter.The second order line is seen at an angle of 30 to the normal what is the wavelength of the light? |
200 nm
430 nm
500 nm
556 nm
|
2 |
In young's slit experiment on interference the ratio of the intensities of a bright band and a dark band is 6 : 1 the ratio of the amplitudes o the interfering waves is |
16
5/3
4
1/4
|
3 |
Signal from a remote control to the device operated by it travels with the speed of: |
Sound
Light
Ultrasonics
Supersonics
|
4 |
When the light is incident on polarizing angle which of the following is completely polarized? |
Reflected light
Refracted light
Both reflected and refracted light
Neither reflected nor refracted light
|
5 |
In the Young's double slit experiment the separation between the slits is halved and the distance between the slits and the screen is doubled the fringe width is |
Halved
Unchanged
Doubled
Quadrupled
|
6 |
For the sustained interference of light the necessary condition is that the two sources should |
Have constant phase difference
Be narrow
Be close to each other
Of same amplitude
|
7 |
If a source of light is moving away from stationary observer then frequency of light wave appears to change because of |
Doppler's effect
Interference
Diffraction
None of the above
|
8 |
When seen in green light the saffron and green portions of our National Flag will appear to be |
Black
Black and green respectively
Green
Green and yellow respectively
|
9 |
Ray optics is valid,when characteristic dimensions are |
Of the same order as the wavelength of light
Much smaller than the wavelength of length
Of the order of one millimeter
Much larger than the wavelength or light
|
10 |
When light travels from one medium to another which are separated by a sharp boundary the characteristic which does not change is |
Velocity
Wavelength
Frequency
Amplitude
|
11 |
Fraunhofer spectrum is a |
Line absorption spectrum
Band absorption spectrum
Line emission spectrum
Band emission spectrum
|
12 |
The sky appears blue because |
Red light is absorbed
Blue light is scattered the most
Blue light is absorbed
It is its natural color
|
13 |
Huygen's wave theory of light cannot explain |
Diffraction
Interference
Polarization
Photoelectric effect
|
14 |
The contrast in the fringes in any interference pattern depends on |
Frings width
Intensity ratio of the sources
Distance between the slits
Wavelength
|
15 |
Which one of the following phenomena is not explained by Huygen's construction of wavefront? |
Refraction
Reflection
Diffraction
Origin of spectra
|
16 |
Light appears to travels in straight lines since |
It is not absorbed by the atmosphere
It is reflected by the atmosphere
Its wavelength is very small
Its velocity is very large
|
17 |
The twinkling of stars is due to |
The fact that stars do not emit light continususly
The refractive index of the earth's atmosphere fluctuate
Intermittent absorption of star light by its own atmosphere
None of these
|
18 |
A prism splits a beam of white light into its seven constituent colors.This is so because |
Phase of different colors is diferent
Amplitude of different colors is different
Energy of different colors is different
Velocity of different colors if different
|
19 |
A sun rise or sun set the sun looks reddish because |
The sun is coldest at these times
Of the effects of reflection and refraction
The sun is hottest at these times
Of the scattering of light
|
20 |
One cannot see through fog because |
Fog absorbs light
The refractive index of fog is infinity
Light suffers total reflection at the droplet in a fog
Light is scattered by the droplets in fog
|