5. You are given four sources of light each one
providing a light of a single colour – red, blue, green and yellow. Suppose
the angle of refraction for a beam of
yellow light corresponding to a particular angle of incidence at the
interface of two media is 90°. Which of the following statements is correct
if the source of yellow light is replaced with that of other lights without
changing the angle of incidence?
(a) The beam of red light would
undergo total internal reflection. (b) The beam of red light would bend
towards normal while it gets refracted through the second medium. (c) The
beam of blue light would undergo total internal reflection. (d) The beam of
green light would bend away from the normal as it gets refracted through the
second medium.
6.The radius of curvature of the
curved surface of a plano-convex lens is 20 cm. If the refractive index of
the material of the lens be 1.5, it will
(a) act as a convex lens only for
the objects that lie on its curved side. (b) act as a concave lens for the
objects that lie on its curved side. (c) act as a convex lens irrespective of
the side on which the object lies. (d) act as a concave lens irrespective of
side on which the object lies
7. The phenomena involved in the
reflection of radiowaves by ionosphere is similar to
(a) reflection of light by a plane
mirror. (b) total internal reflection of light in air during a mirage. (c)
dispersion of light by water molecules during the formation of a rainbow. (d)
scattering of light by the particles of air.
8. A car is moving with at a
constant speed of 60 km h–1 on a straight road. Looking at the rear view
mirror, the driver finds that the car following him is at a distance of 100 m
and is approaching with a speed of 5 km h –1. In order to keep track of the
car in the rear, the driver begins to glance alternatively at the rear and
side mirror of his car after every 2 s till the other car overtakes. If the
two cars were maintaining their speeds, which of the following statement (s)
is/are correct?
(a) The speed of the car in the
rear is 65 km h–1. (b) In the side mirror the car in the rear would appear to
approach with a speed of 5 km h–1 to the driver of the leading car. (c) In
the rear view mirror the speed of the approaching car would appear to
decrease as the distance between the cars decreases. (d) In the side mirror,
the speed of the approaching car would appear to increase as the distance
between the cars decreases.
9. Consider an extended object
immersed in water contained in a plane trough. When seen from close to the
edge of the trough the object looks distorted because
(a) the apparent depth of the
points close to the edge are nearer the surface of the water compared to the
points away from the edge. (b) the angle subtended by the image of the object
at the eye is smaller than the actual angle subtended by the object in air.
(c) some of the points of the object far away from the edge may not be
visible because of total internal reflection. (d) water in a trough acts as a
lens and magnifies the object.
10. An astronomical refractive
telescope has an objective of focal length 20m and an eyepiece of focal
length 2cm.
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