1. The air layer of atmosphere whose temperature is less then the hot layer behave as optically,
(a) denser medium
(b) rarer medium
(c) inactive medium
(d) either denser or rarer medium
ANS: denser medium
2. Refraction of light by the earth’s atmosphere due to
variation in air density is called
(a)
atmospheric reflection
(b) atmospheric dispersion
(c) atmospheric scattering
(d) atmospheric refraction
ANS: atmospheric refraction
3. The word optical density of
atmosphere refers to-
(a) thickness of atmosphere
(b) brightness of atmosphere
(c) degree to which atmosphere
reduces intensity of light passing through it
(d) degree to which atmosphere
focuses light
ANS: degree to which atmosphere
reduces intensity of light passing through it.
4. Twinkling of stars is due to atmospheric
(a) dispersion of light by water droplets
(b) atmospheric refraction of light by different
layers of varying refractive indices
(c) scattering of light by dust particles
(d) internal reflection of light by clouds.
ANS: atmospheric refraction of light
by different layers of varying refractive indices
5.
As light from a far off star come down towards the earth
(a) it bends away from the
normal
(b) it bends towards the normal
(c) it does not bend at all
(d) it reflects back
ANS: it bends towards the normal
6. The stars appear shifted from
their actual position due to the phenomenon of,
(a) diffraction of light
(b) scattering of light
(c) refraction of light
(d) internal reflection of light
ANS: refraction of light
7. The stars twinkle but the planets do
not twinkle at night because-
(a) the stars are big but the
planets are smaller
(b) the stars are very much
nearer but planets are far off
(c) the stars are far off but
planets are nearer to the earth
(d) planets produce light which
is reflected by stars
ANS: the stars are far off but
planets are nearer to the earth
8.
The planets do not twinkle because-
(a) atmospheric refraction does
not take place
(b) planets are equivalent to a point
source
(c) planets are equivalent to an
extended source
(d) planets do not have
atmosphere
ANS: planets are equivalent to an
extended source
9. Advanced sunrise and delayed sunset
are explained on the basis of
(a) dispersion of light
(b) scattering of light
(c) Tyndall effect
(d) atmospheric refraction
ANS: atmospheric refraction
10. The Sun is visible before the
sunrise and after the sunset because of the phenomenon of ______.
(a) reflection
(b) refraction
(c) dispersion
(d) polarization
ANS: refraction
11.
A setting sun appears to be at an altitude higher than it really is.
This is because,
(a) absorption of light
(b) reflection of light
(c) refraction of light
(d) dispersion of light
ANS: refraction of light
12. Due to atmospheric refraction
of sunlight, the time from sunrise to sunset is lengthened by about
(a) 2 min
(b) 4 min
(c) 5 min
(d) 6 min
ANS: 4 min
13. Why does sun exhibit an
elliptical shape at the time of rising and setting?
(a) due to refraction
(b) due to reflection
(c) due to scattering
(d) due to dispersion
ANS: due to refraction
14.
Apparent position of the star appears raised due to-
(a) atmospheric refraction
(b) scattering of light
(c) both (A) and (B)
(d) internal reflection and
refraction
ANS: atmospheric refraction
15. Which of the following is not
caused by the atmospheric refraction?
(a) Twinkling of stars at night
(b) Sun becoming visible 2
minutes before the sunrise
(c) Sun appears red at sunset
(d) Sun appears higher in the
sky than it actually is
ANS: Sun appears red at sunset
16. Which of the following is not
an example of atmospheric refraction?
(a) Delayed sunset
(b) Sun appears white at noon
(c) Flattening of the Sun’s disc
at sunrise
(d) Flickering of kitchen window
mesh through hot vapours rising above boiling water
ANS: sun appears white at noon
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