-
Which one of the following materials cannot be used to make a lens?
(a) Water (b) Glass
(c) Plastic (d) Clay
View Answer play_arrow
-
The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object?
(a) Between the focus and the centre of curvature
(b) At the centre of curvature
(c) Beyond the centre of curvature
(d) Between the pole of the mirror and its focus
View Answer play_arrow
-
Where should an object be placed in front of a convex lens to get a real image of the size of object?
(a) At the principal focus of lens
(b) At twice the focal length
(c) At infinity
(d) Between optical centre of lens and its principal focus
View Answer play_arrow
-
A spherical mirror and a thin spherical lens have each a focal length of – 15 cm. The mirror and lens are likely to be
(a) Both concave
(b) Both convex
(c) Mirror is concave and lens is convex
(d) Mirror is convex and lens is concave
View Answer play_arrow
-
No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be
(a) Plane (b) Concave
(c) Convex (d) Either plane or convex
View Answer play_arrow
-
Which of the following lenses would you prefer to use while reading small letters found in a dictionary?
(a) A convex lens of focal length 50 cm
(b) A concave lens of focal length 50 cm
(c) A convex lens of focal length 5 cm
(d) A concave lens of focal length 5 cm
View Answer play_arrow
-
We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? What is the nature of the image? Is the image larger or smaller than the object? Draw a ray diagram to show the image formation in this case.
View Answer play_arrow
-
Name the type of mirror used in the following situations.
(a) Headlights of a
(b) Side/rear-view mirror of a
(c) Solar furnace
Support your answer with reason.
View Answer play_arrow
-
One half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.
View Answer play_arrow
-
An object 5 cm in length is held 25 cm away from a
converging lens of focal length 10 cm. Draw the ray diagram and find the
position, size and the nature of the image formed.
View Answer play_arrow
-
A concave lens of focal length 15
cm forms an image 10 cm from the lens. How far is the object placed from the
lens? Draw the ray diagram.
View Answer play_arrow
-
An object is placed at a distance
of 10 cm from a convex mirror of focal length 15 cm. Find the position and
nature of the image.
View Answer play_arrow
-
The magnification produced by a
plane mirror is
.
What does this mean?
View Answer play_arrow
-
An object 5.0 cm in length is
placed at a distance of 20 cm in front of a convex mirror of radius of
curvature 30 m. Find the position of the image, its nature and size.
View Answer play_arrow
-
An object of size 7.0 cm is
placed at 27 cm in front of a concave mirror of focal length 18 cm. At what
distance from the mirror should a screen be placed, so that a sharp focused
image can be obtained? Find the size and the nature of the image.
View Answer play_arrow
-
Find the focal length of a lens
of power ? 2.0 D. What type of lens is this?
View Answer play_arrow
-
A doctor has prescribed a
corrective lens of power + 1.5 D. Find the focal length of the lens. Is the
prescribed lens diverging or converging?
View Answer play_arrow
-
Define the principal focus of a concave mirror.
View Answer play_arrow
-
The radius of curvature of a spherical mirror is 20 cm. What is its focal length ?
View Answer play_arrow
-
Name a mirror that can give an erect and enlarged image of an object.
View Answer play_arrow
-
Why do we prefer a convex mirror as a rear-view mirror in vehicles?
View Answer play_arrow
-
Find the focal length of a convex mirror whose radius of curvature is 32 cm.
View Answer play_arrow
-
A concave mirror produces three times magnified real image of an object placed at 10 cm in front of it.
View Answer play_arrow
-
A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal ? Why?
View Answer play_arrow
-
Light enters from air to glass having refractive index 1.5. What is the speed of light in glass? The speed of light in vacuum is 3 x 108 m s-1.
View Answer play_arrow
-
Find out, from table, the medium having highest optical density. Also find the medium with lowest optical density.
View Answer play_arrow
-
You are given kerosene, turpentine and water. In which of these does the light travel fastest?
View Answer play_arrow
-
The refractive index of diamond is 2.42. What is the meaning of this statement?
View Answer play_arrow
-
Define 1 dioptre of power of a lens.
View Answer play_arrow
-
A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.
View Answer play_arrow
-
Find the power of a concave lens of focal length 2 m.
View Answer play_arrow
-
question_answer32)
Which of the following can make a
parallel beam of light when light from a point source is incident on it?
(a) Concave mirror as well as
convex lens
(b) Convex mirror as well as
concave lens
(c) Two plane mirrors placed at
90° to each other
(d) Concave mirror as well as
concave lens
View Answer play_arrow
-
question_answer33)
A 10 mm long awl pin is placed
vertically in front of a concave mirror. A 5 mm long image of the awl pin is
formed at 30 cm in front of the mirror. The focal length of this mirror is
(a) -30 cm (b)
-20 cm (c) - 40 cm (d) -60
cm
View Answer play_arrow
-
question_answer34)
Under which of the following
conditions, a concave mirror can form an image larger than the actual object?
(a) When the object is kept at a
distance equal to its radius of curvature.
(b) When object is kept at a
distance less than its focal length
(c) When object is placed
between the focus and centre of curvature
(d) When object is kept at a
distance greater than its radius of curvature
View Answer play_arrow
-
question_answer35)
Figure shows a ray of light as
it travels from medium A to medium B. Refractive index of the medium B relative
to medium A is
(a) (b) (c) (d)
View Answer play_arrow
-
question_answer36)
A light ray enters from medium A
to medium B as shown in the figure. The refractive index of medium 6 relative
to A will be
(a) greater than
unity (b) less than unity
(c) equal to
unity (d) zero
View Answer play_arrow
-
question_answer37)
Beams of light are incident
through the holes A and B and emerge out of box through the holes C and D
respectively as shown in the figure. Which of the following could be inside the
box?
(a) A rectangular glass
slab (b) A convex lens
(c) A concave
lens (d) A prism
View Answer play_arrow
-
question_answer38)
A beam of light is incident through the
holes on side A and emerges out of the holes on the other face of the box as
shown in the figure. Which of the following could be inside the box?
(a) Concave
lens (b)
Rectangular glass slab
(c)
Prism (d) Convex
lens
View Answer play_arrow
-
question_answer39)
Which of the following statements is
true?
(a) A convex lens has 4 dioptre
power having a focal length 0.25 m
(b)A convex lens has 4 dioptre
power having a focal length -0.25 m
(c) A concave lens has 4 dioptre
power having a focal length 0.25 m
(d) A concave lens has 4 dioptre
power having a focal length - 0.25 m
View Answer play_arrow
-
question_answer40)
Magnification produced by a rear
view mirror fitted in vehicles
(a) is less than one
(b) is more than one
(c) is equal to one
(d) can be more than or less
than one depending upon the position of the object in front of it.
View Answer play_arrow
-
question_answer41)
Rays from sun converge at a point 15 cm
in front of a concave mirror. Where should an object be placed so that size of
its image is equal to the size of the object?
(a) 15 cm in front of the mirror
(b) 30 cm in front of the mirror
(c) between 15 cm and 30 cm in
front of the mirror
(d) more than 30 cm in front of
the mirror
View Answer play_arrow
-
question_answer42)
A full length image of a distant
tall-building can definitely be seen by using
(a) a concave
mirror (b) a convex
mirror
(c) a plane
mirror (d) both
concave as well as plane mirror
View Answer play_arrow
-
question_answer43)
In torches, search lights and
headlights of vehicles, the bulb is placed
(a) between the pole and the
focus of the reflector
(b) very near to the focus of
the reflector
(c) between the focus and centre
of curvature of the reflector
(d) at the centre of curvature
of the reflector
View Answer play_arrow
-
question_answer44)
The laws of reflection hold good
for
(a) plane mirror
only (b) concave mirror
only
(c) convex mirror
only (d) all mirrors
irrespective of their shape
View Answer play_arrow
-
question_answer45)
The path of a ray of light coming from
air passing through a rectangular glass slab traced by four students shown as
A, B, C and D in the figure.
Which one of them is correct?
(a) A (b)B
(c)C (d)D
View Answer play_arrow
-
question_answer46)
You are given water, mustard oil, glycerin
and kerosene. In which of these media, a ray of light incident obliquely at
same angle would bend the most?
(a) Kerosene (b)
Water (c) Mustard oil (d) Glycerin
View Answer play_arrow
-
question_answer47)
Which of the following ray diagrams is
correct for the ray of light incident on a concave mirror as shown in figure?
(a) A (b)
B (c) C (d)
D
View Answer play_arrow
-
question_answer48)
Which of the following ray diagrams is
correct for the ray of light incident on a lens shown in figure?
(a) A (b)B
(c)C (d)D
View Answer play_arrow
-
question_answer49)
A child is standing -in front of a magic
mirror. She finds the image of her head bigger, the middle portion of her body
of the same size and that of the legs smaller. The following is the order of
combinations for the magic mirror from the top.
(a) Plane, convex and
concave (b) Convex, concave and plane
(c) Concave, plane and
convex (d) Convex, plane and concave
View Answer play_arrow
-
question_answer50)
In which of the following, the image of
an object placed at infinity will be highly diminished and point sized?
(a) Concave mirror only
(b) Convex mirror only
(c) Convex lens only
(d) Concave mirror, convex
mirror, concave lens and convex lens
View Answer play_arrow
-
question_answer51)
Identify the device used as a
spherical mirror or lens in following cases, when the image formed is virtual
and erect in each case.
(a) Object is placed between
device and its focus, image formed is enlarged and behind it
(b) Object is placed between the
focus and device, image formed is enlarged and on the same side as that of the
object
(c) Object is placed between
infinity and device, image formed is diminished and between focus and optical
centre on the same side as that of the object
(d) Object is placed between
infinity and device, image formed is diminished and between pole and focus,
behind it
View Answer play_arrow
-
question_answer52)
Why does a light ray incident on
a rectangular glass slab immersed in any medium emerges parallel to itself?
Explain using a diagram.
View Answer play_arrow
-
question_answer53)
A pencil when dipped in water in
a glass tumbler appears to be bent at the interface of air and water. Will the
pencil appear to be bent to the same extent, if instead of water we use liquids
like, kerosene or turpentine? Support your answer with reason.
View Answer play_arrow
-
question_answer54)
How is the refractive index of a
medium related to the speed of light? Obtain an expression for refractive index
of a medium with respect to another in terms of speed of light in these two
media?
View Answer play_arrow
-
question_answer55)
Refractive index of diamond with
respect to glass is 1.6 and absolute refractive index of glass is 1.5. Find out
the absolute refractive index of diamond.
View Answer play_arrow
-
question_answer56)
A convex lens of focal length 20
cm can produce a magnified virtual as well as real image. Is this a correct
statement? If yes, where shall the object be placed in each case for obtaining
these images?
View Answer play_arrow
-
question_answer57)
Sudha finds out that the sharp
image of the window pane of her science laboratory is formed at a distance of
15 cm from the lens. She now tries to focus the building visible to her outside
the window instead of the window pane without disturbing the lens. In which
direction will she move the screen to obtain a sharp image of the building?
What is the approximate focal length of this lens?
View Answer play_arrow
-
question_answer58)
How are power and focal length
of a lens related? You are provided with two lenses of focal length 20 cm and
40 cm, respectively. Which lens will you use to obtain more convergent light?
View Answer play_arrow
-
question_answer59)
Under what condition in an arrangement
of two plane mirrors, incident ray and reflected ray will always be parallel to
each other, whatever maybe angle of incidence. Show the same with the help of
diagram.
View Answer play_arrow
-
question_answer60)
Draw a ray diagram showing the path of
rays of light when it enters with oblique incidence (i) from air into water;
(ii) from water into air.
View Answer play_arrow
-
question_answer61)
Draw ray diagrams showing the image
formation by a concave mirror when an object is placed
(a) between pole and focus of
the mirror
(b) between focus and centre of
curvature of the mirror
(c) at centre of curvature of
the mirror
(d) a little beyond centre of
curvature of the mirror at infinity
View Answer play_arrow
-
question_answer62)
Draw ray diagrams showing the
image formation by a convex lens when an object is placed
(a) between optical centre and
focus of the lens
(b) between focus and twice the
focal length of the lens
(c) at twice the focal length of
the lens at infinity
(d) at the focus of the lens
View Answer play_arrow
-
question_answer63)
Write laws of refraction. Explain the
same with the help of ray diagram, when a ray of light passes through a
rectangular glass slab.
View Answer play_arrow
-
question_answer64)
Draw ray diagrams showing the
image formation by a concave lens when an object is placed
(a) at the focus of the lens
(b) between focus and twice the
focal length of the lens
(c) beyond twice the focal
length of the lens
View Answer play_arrow
-
question_answer65)
Draw ray diagrams showing the
image formation by a convex mirror when an object is placed
(a) at
infinity
(b) at finite distance from the
mirror
View Answer play_arrow
-
question_answer66)
The image of a candle flame
formed by a lens is obtained on a screen placed on the other side of the lens.
If the image is three times the size of the flame and the distance between lens
and image is 80 cm, at what distance should the candle be placed from the lens?
What is the nature of the image at a distance of 80 cm and the lens?
View Answer play_arrow
-
question_answer67)
Size of image of an object by a
mirror having a focal length of 20 cm is observed to be reduced to 1/3rd to its
size. At what distance, the object has been placed from the mirror? What is the
nature of the image and the mirror?
View Answer play_arrow
-
question_answer68)
Define power of a lens. What is
its unit? One student uses a lens of focal length 50 cm and another of -50 cm.
What is the nature of the length and its power used by each of them?
View Answer play_arrow
-
question_answer69)
A student focused the image of a
candle flame on a white screen using a convex lens. He noted down the position
of the candle, screen and the lens as under
position of candle =12.0 cm
position of convex lens = 50.0
cm
position of the screen = 88.0 cm
(i) What is the focal length of
the convex lens?
(ii) Where will the image be
formed, if he shifts the candle towards the lens at a position of 31.0 cm?
(iii) What will be the nature of
the image formed, if he further shifts the candle towards the lens?
(iv) Draw a ray diagram to show
the formation of the image in case as said above.
View Answer play_arrow