/
5°
7.8°
10.6°
20°
Angle of a prism is 30° and its refractive index is and one of the surface is silvered. At what angle of incidence, a ray should be incident on one surface so that after reflection from the silvered surface, it retraces its path?
30°
60°
45°
For a material, the refractive indices for red, violet and yellow colour light are respectively 1.52, 1.64 and 1.60. The dispersive power of the material is ____.
2
0.45
0.2
0.045
Band spectrum is produced by ____.
H
He
H2
Na
The band spectra (characteristic of molecular species) are due to emission of radiation ____.
gaseous state
liquid state
solid state
All of three states
Line spectrum was first of all theoretically explained by ____.
Swan
Fraunhofer
Kirchoff
Bohr
The spectrum of iodine gas under white light is ____.
only violet
bright lines
only red lines
some black bands in continuous spectrum
Continuous spectrum is not due to ____.
hydrogen flame
electric bulb
kerosene oil lamp flame
candle flame
Fraunhofer lines are produced by in the ____.
the element present in photosphere of sun
the elements present in the chromospheres of the sun
the vapour of the element present in the chromospheres of the sun
the carbon dioxide present in the atmosphere
A medium is said to be dispersive, if ____.
light of different wavelengths propagate at different speeds
light of different wavelengths propagate at same speed but has different frequencies
light is gradually bent rather than sharply refracted at an interface between the medium and air
light is never totally internally reflected
A ray of light is incident at an angle of 60° on one face of a prism of angle 30°. The ray emerging out of the prism makes an angle of 30° with the incident ray. The emergent ray is ____.
normal to the face through which it emerges
inclined at 30° to the face through which it emerges
inclined at 60° to the face through which it emerges
None of the above
/
Dispersion can take place for ____.
transverse waves only but not for longitudinal waves
longitudinal waves only but not for transverse waves
both transverse and longitudinal waves
Neither transverse nor longitudinal waves
Emission spectrum of gas ____.
is a line spectrum
is a band spectrum
is a continuous spectrum
does not fall in the visible region
A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to of the angle of the prism. The angle of deviation is ____.
45°
39°
20°
30°
The true statement is ____.
the order of colours in the primary and the secondary rainbows is the same
the intensity of colours in the primary and the secondary rainbows is the same
the intensity of light in the primary rainbow is greater and the order of colours is the same than the secondary rainbow
the intensity of light for different colours in primary rainbow is greater and the order of colours is reverse than the secondary rainbow
What is the colour of sky as seen from the earth, if there were no atmosphere?
Black
Blue
Orange
Red
When light emitted by a white hot solid is passed through a sodium flame, the spectrum of the emergent light will show ____.
two dark lines in the yellow region
all colours from violet to red
no colours at all
A ray of monochromatic light is incident on one refracting face of a prism of angle 75°. It passes through the prism and is incident on the other face at the critical angle. If the refractive index of the material of the prism is , the angle of incidence on the first face of the prism is ____.
30°
45°
60°
0°
At the time of total solar eclipse, the spectrum of solar radiation would be ____.
a large number of dark Fraunhofer lines
a less number of dark Fraunhofer lines
no lines at all
all Fraunhofer lines changed into brilliant colours