CBSE
Multiple Choice QuestionsIn a Young's double slit experiment the intensity of light when slit is at distance A from central is I. What will be the intensity at the distance of slit is ?
The near point of distinct vision is at 1 m for an elderly person. What power of lens is to be used to bring the near point to the minimum distance of distinct vision (25 cm)?
2.5 D
3 D
3.5 D
4 D
Assertion: A secondary rainbow have inverted colours than the primary rainbow.
Reason: The secondary rainbow is formed by single total internal reflection.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
In Young's double slit experiment, fringe order is represented by m, then fringe width is
Independent of m
Directly proportional to m
Directly proportional to ( 2m + 1 )
Inversely proportional to (2m + 1 )
In a Young's double slit experiment the spacing between the slits is 0.3 mm and the screen is kept at a distance of 1.5 m. The second bright fringe is found 6 mm from the central fringe. The wavelength of the light used in the experiment is
625 nm
600 nm
550 nm
500 nm
Assertion: When light ray is incident at polarising angle on glass, refracted light is partially polarised.
Reason: The intensity of light decreases in polarisation.
If both assertion and reason are true and reason the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Assertion: A laser beam of 0.2 W power can drill holes through a metal sheet, whereas a 1000 W torch-light cannot.
Reason: The frequency of laser light is much higher than that of torch light.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
A light ray is incident on a glass slab, it is partially reflected and partially transmitted. Then the reflected ray is
completely polarised and highly intense.
partially polarised and poorly intense.
partially polarised and highly intense.
completely polarised and poorly intense.
Polaroid glass is used in sun glasses because
it reduces the light intensity to half on account of polarisation
it is fashionable
it has good colour
it is cheaper
Resolving power of reflecting microscope increase with
decrease in wavelength of incident light
increase in wavelength of incident light
increase in diameter of objective lens
none of these
