1. An object is placed between two plane
mirrors inclined at an angle of 45° to each other. How many images do you
expect to see?
2. A
convex mirror is held in water. What should be the change in its focal length?
3.If
the light from the Sun subtend an angle Q at the pole of a concave mirror of
focal length f, where will it converge? Also find the diameter of the image.
Draw the necessary ray diagram.
4. When
does Snell’s law of refraction fail?
5. How
does the frequency of a beam of ultraviolet light changes when it goes from air
to glass?
6.State
two conditions under which a ray of light suffering refraction from medium 1 to
medium 2 does not undergo any change in direction
7.Name
the factor on which lateral shift produced by glass slab depends?
8. A
glass lens is immersed in water. How is the power of the lens affected?
9. Why
is the power of a lens is measured as reciprocal of focal length? Give
reason.
10.A convex
lens is made of a material of refractive index m1 when
placed in a medium of refractive index m2, behaves as a
diverging lens. How are m1 and m2 related?
11. An
object is held at a distance of 60 cm from a convex mirror of focal length 20
cm. At what distance from the mirror, should a plane mirror be held so that
images in the two mirrors coincide?(ans. 22.5 cm)
12.How do
you find the rough focal length of a convex lens? Is the same method applicable
to a concave lens?
13. Which
factors determine the focal length of a lens?
14. The
formula for linear magnification of a spherical mirror is m=h’/h = -v/u. What
determines the sign of m? What is the significance of this sign?
15.A convex
lens made of material of refractive index n2 is kept in a
medium of refractive index n1. A parallel beam of light is incident
on the lens. Compare the path of rays of light emerging from the convex lens if
(i) n12 (ii)n1=n2 (iii)
n1>n2
16. A
concave lens of focal length 25 cm and a convex lens of focal length 20 cm are
placed in contact with each other. What is the power of this combination? Also,
calculate focal length of this combination. (ans. 1m)
17. A
convergent lens of power 8D is combined with a divergent lens of power -10 D.
Calculate focal length of the combination. (ans.-0.5 m)
18. A
concave lens has a focal length of 15 cm. At what distance should an object
from the lens be placed so that it forms an image at 10 cm from the lens? Also
find the magnification of the lens.
19. Under
what condition in an arrangement of two plane mirrors, incident ray and
reflected ray will always be parallel to each other, whatever be the angle of
incidence? Show the same with the help of diagram.
20. How much
time will light take to cross 2 mm thick glass pane if refractive index of
glass is 3/2? (ans. 10-11s)
21. Light
travel from rarer medium 1 to a denser medium 2. The angle of incidence and
refraction are respectively 45° and 30°. Calculate the refractive index of
second medium with respect to the first medium.
22. A pond
of depth 20 cm is filled with water of refractive index 4/3. Calculate apparent
depth of the tank when viewed normally.
23. Light of
wavelength 500nm in air enters a glass plate of refractive index 1.5. Find
(a)speed. (b)frequency, and (c)wavelength of light in glass. Assume that the
frequency of light remains the same in both media.
24. A myopic
person prefers to remove his spectacles while reading a book. Give reason.
25. A hypermetropic person prefers to remove his spectacles while driving a vehicle. Give reason.
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