Multiple Choice QuestionsSolid targets of different elements are bombarded by highly energetic electron beams. The frequency (f) of the characteristic X-rays emitted from different targets varies with atomic number Z as
f ∝
f ∝ Z2
f ∝ Z
f ∝ Z3/2
When exposed to sunlight, thin films of oil on water often exhibit brilliant colours due to the phenomenon of
interference
diffraction
dispersion
polarisation
Assertion: The clouds in sky generally appear to be whitish.
Reason: Diffraction due to clouds is efficient in equal measure at all wavelengths.
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
C.
If assertion is true but reason is false
The clouds consists of dust particles and water droplets. Their size is very large as compared to the wavelength of the incident light from the sun. So there is very little scattering of light. Hence the light which we receive through the clouds has all the colours of light. As a result of this, we receive almost white light. Therefore, the cloud are generally white.
Sodium lamps are used in foggy conditions because
yellow light is scattered less by the fog particles
yellow light is scattered more by the fog particles
yellow light is unaffected during its passage through the fog
wavelength of yellow light is the mean of the visible one
A monochromatic beam of light is used for the formation of fringes on the screen by illuminating the two slits in the Young's double slit interference experiment. When a thin film of mica is interposed in the path of one of the interfering beams then
the fringe width increases
the fringe width decreases
the fringe width remains the same but the pattern shifts
the fringe pattern disappears
When a compact disc is illuminated by a source of white light, coloured lines are observed. This is due to
dispersion
diffraction
interference
refraction
Assertion: At the first glance, the top surface of the Morpho butterfly's wing appears a beautiful blue-green. If the wing moves the colour changes.
Reason: Different pigments in the wing reflect light at different angles.
If both assertion and reason are true and reason is 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 famous painting was painted by not using brush strokes in the usual manner, but rather a myriad of small colour dots. In this painting the colour you see at any given place on the painting changes as you move away.
Reason: The angular separation of adjacent dots changes with the distance from the painting.
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
Assertion: Crystalline solids can cause X-rays to diffract.
Reason: Interatomic distance in crystalline solids is of the order of 0.1 nm.
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
When a beam of light is used to determine the position of an object, the maximum accuracy is achieved if the light is
polarised
of longer wavelength
of shorter wavelength
of high intensity
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