File No.33/06/18/11/2014
VI CLASS - IIT/N.T.S.E FOUNDATION - OLYMPIAD
ANDHRA PRADESH - TELANGANA
2014-2015 PROGRAM M E
2nd - CHAPTER - SOLUTIONS
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2. LIGHT
1.
We are able to see moon because It reflects sunlight
2.
It is not possible to see a burning candle by using a bent pipe because Light travels in straight line
3.
During shadow formation, penumbra is seen Outside the umbra
4.
Shadows are real
5.
A camera flash is used in front of a mirror to take a photograph of the image of an object in the
mirror,then: the photograph of the image will not show anything except white colour
6.
A periscope in a submarine helps in viewing those objects that are above the surface of water
7.
The image formed by a plane mirror cannot be Smaller than the object
8.
The number of images of an object placed between two plane prallel mirrors is Infinite
9.
Man made sources of light: are incandescent lamp, Fluorescent lamp and Hurricane lamp.
10.
The image formed by a pinhole camera is real and inverted.
11.
The Earth is a non-luminous body.
12.
Fire is a luminous body.
13.
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A thin layer of water is transparent but a
vey thick
layer of water is Translucent
14.
You can see through a car window because the window is transparent
15.
Through oild papers only a part of the light pass through it because oild paper is transferent.
16.
The speed of light with the rise in the temperature of the medium Remains unaltered.
17.
Air is not visible because it is nearly a perfectly transparent substance and Neither absorbs nor reflects light
and transmits whole light.
18.
We are able to see things because The rays of sun fall on the objects
19.
Lunar eclipse takes place on Full moon
20.
To an astronaut the outer space apears black
1.
The light from torch when falls on a key form, a shadow on the screen behind the card as shown in the
figure. As the torch is moved away from the card the shadow will Become smaller
Car reversing at a speed of 2 m/s. The image of truck appears to approach driver will be
2 m/s + 2 m/s = 4 m/s.
2.
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File No.33/06/18/11/2014
3.
VI CLASS - IIT/N.T.S.E FOUNDATION - OLYMPIAD
400
Given

i.e, i  400 ,
  ? Acc. to laws of reflection r  i  400
   i  r  40  40  80 0
300
4.
30 0
600
From fig., i  300 , r  300
5.
The child a looks into mirror, the distance of child B appear to be distance between A & B + 2 (image
distance of A)
7m
2m
A
B
= 7 + 2(2)
= 11m.
6.
The number of images formed (n) 

7.
360
1

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360
1
45
= 8-1
=7
n=5
360
 1 5

360
6

8.
Given   300
n
9.
  600
360
360
 1
 1 11

30
Given two plane mirror are facing each other i.e, the two mirror are parallel to each other i.e,
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  00 , n  
10.
  x0
Given n = 5. then  = ?
n
360
360
360
 1  5  1
 
 600


6
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11.
VI CLASS - IIT/N.T.S.E FOUNDATION - OLYMPIAD
Given two plane mirror are facing each other i.e, the two mirror are parallel to each other i.e,
  00 , n  
12.
13.
According to laws of reflection, angle of reflection.
 The ray emerges (reflects back) at the same angle i.e., 300
From the below figure plane of reflection is BON
14.
From the above figure plane of incidence is AON
15.
From the above figure d represents angle of deviation
16.
From the above figure glancing angle of incidence is MOA
17.
At which of the following times, the length of a shadow of a tree will be longest at 9 AM
18.
Umbra and penumbra are clearly visible when both source of light and the object are small and placed
nearer to each other
19.
A ray of light strikes a plane mirror along the normal, the angle of incidence is zero degree
20.
The law reflection is Angle i = Angle r
BRAIN TWISTERS
1.
2.
3.
4.
5.
6.
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7.
8.
An opaque object does not allow light to pass through it, reflects light falling through it.
The correct statments are in a glow worm the energy produced during a chemical reaction in, its body is
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released in the form of light only, an electric bulb glows, when the filament attains very temperature due to
the passage of current, due to the powerful reactions taking place in the sun the energy produced by the
sun consists of light and heat and stars are non luminous bodies.
In case of plane mirror object distance = image distance, object size = image size and the image formed is
virtual.
W, K showns lateral inversion.
Virtual image cannot be taken on screen and real image always be taken on screen are correct.
a. Stars
b. Human beings
c. Air
d. Torch light
e. Frosted glass
a. Air
b. Pure water
c. Wood
d. Glow warm
-
Natural sources of light
Opaque
Transparent
Artificial source of light
Translucent
Heterogeneous medium
Homogeneous medium
Opaque medium
Bioluminescence
a. luminous object
-
sun
b. non - luminous object
-
moon, benzene, tracing paper
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9.
10.
11.
12.
13.
14.
15.
VI CLASS - IIT/N.T.S.E FOUNDATION - OLYMPIAD
c. transparent object
-
benzene
d. translucent object
-
tracing paper
a. regular reflection
-
polished smooth surfaces
b. irregular reflection
-
rough surface
c. angle of incidence
-
Angle between normal and incident ray
d. angle of reflection
-
angle between normal and reflected.
In case of regular reflection (or) irregular reflection , angle of incidence is equal to angle of reflection, both
regular and irregular reflection obeys laws of reflection.
Both Assertion and Reason are correct and Reason explains Assertion.
Lunar eclipse is not cast on every full moon light.
The shadow of the earth reach the moon on every full moon light.
Assertion is correct and Reason is in correct.
Planets are not not luminous bodies
The sun is the nearest to us from which the earth receives most of the light.
Both Assertion and Reason are correct but Reason does not explain Assertion.
Only a point source forms a complete umbra.
An extended source of light forms both umbra and penumbra.
Both Assertion and Reason are correct but Reason does not explain Assertion.
Moon is a luminous source of light. A glow worm is a natural source of light.
So, Assertion is wrong and reason is correct.
Shadows are formed due to rectilinear propagation of light.
When the position of the earth is between sun and moon , lunar eclipse is formed .
Both Assertion and Reason are correct and Reason explains Assertion.
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16.
17.
18.
From the above figure angle of incidence is AON .
From the above figure angle of reflection is BON
From the above figure the relation between i and r is i  r
19.
The speed of light in air is 3 108 m / s
20.
The number of images formed by two mirrors at 400 to each other is
n
360
 1= 8.

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
360
1

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File No.33/06/18/11/2014
1.
2.
3.
4.
5.
6.
7.
8.
9.
VI CLASS - IIT/N.T.S.E FOUNDATION - OLYMPIAD
The ratio of incident angle to the reflected angle is 1:1
Angle of deviation is ‘d’ ,
angle of glancing when a ray incident on a plane mirror is d/2
A ray of light ofter reflection from a plane mirror suffers a deviation of 800, then the anlge between incident
and reflected ray is 1000.
Deviation angle = D = 180° – 2 × 60° = 60°
The correct options is three images are formed for an object kept in between two mirrors placed perpendicular
to each other, if the mirror is displaced by a distance ‘X’ , towards or aways from the object the image is
displaced ‘2X’.
Regular reflection occurs when a beam of light falls on a smooth and polished surface
Irregular reflection occurs when a beam of light falls on a rough surface.
A plane mirror reflects a beam light to form a real image. The incident beam is convergent.
Two plane mirrors are placed perpendicular to each other. A ray strikes one mirror and after reflection falls
on the second mirror. The ray after reflection from the second mirror will be parallel to the original ray.
Given two mirrors are parallel to each other then  =00
n
360
1  

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10.
If a number of images of a candle flame are seen in a thick mirror, then the second image is the brightest.
11.
  1800  2i
Given  = 900 , i  ?
W.K.T.   180  2i  90  180  2i
2i = 90
i = 450.
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12.
13.
Velocity of object and image are same but opposite in direction
so, his image velocity = -6 m/s
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14.
VI CLASS - IIT/N.T.S.E FOUNDATION - OLYMPIAD
Room has volune so, h it depend on l, b, h,
If a man stands in a room at centre.
The hight of ceeling = H
The length of shortest plane mirror fixed on wall infront of the man, so that the man can see the full image
of the wall behind him is
H
.
3
15.
6.0 from the person
16.
From the diagram, XC is the incident ray and AXB is the angle of incidence while BXC is the angle of
reflection
B
C
A
P
17.
Q
X
Position of man A is fired. Man B moves 4 m forward so, his position from mirror is
(12 - 4)m = 8m
4m
2m
8m
man A
man A
man B
18.
10m
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man B
Therefore distance between man A and image of B (for new position) = 2+8 = 10m
Assuming the distance between the man and the mirror at time t = 0 is x m. The distance between the
image and the mirror at time t = 0 s is therefore also x m. After 1s, the mirror would have moved 5m away
from the mirror would have also increased by 5m. The distance between the man and his image therefore
increases by 10m in 1s. The speed of the man moving away from his image is therefore 10ms-1
mirror
5ms 1
man
19.
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20.
When a light ray is reflected repeatedly by a set of parallel plane mirrors, the intensity of light rays decreases
after some reflections. This is because of absortion of some amount of light by mirrors.
When the distance between the object and the plane mirror increases because the size of the image will
become less than the size of the object.
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