Selina Textbook Solutions: Light | Physics Class 6 ICSE PDF Download

 Page 1


? Synposis 
? Light itself is not visible, but in the presence of light other objects become visible 
A. 
? Light is defined as the external physical cause that affects the eye to produce the 
sensation of vision. 
? Two types of sources of light are: 
(1) Natural sources such as sun, stars andjugnu. 
(2) Artificial sources such as fire, electric lamp, electric tube light, a burning 
candle, a kerosene lamps heated bodies, etc. 
? The bodies which themselves emit light are called luminous bodies. Examples: 
torch, electric lamps electric tube light, burning candle, kerosene lamp, sun, stars. 
Jugnu etc. 
? The bodies which do not emit light by their own, but they become visible because 
of the light falling on them from a luminous body, are called non-luminous bodies. 
Examples: moon, earth, table, book, chair etc. 
? A medium which allows the passage of light through it easily, is called a 
transparent medium. Examples: glass, air, water etc. 
? A medium which allows only a small amount oflight to pass through it, is called a 
translucent medium. Examples: ground glass, tracing paper etc. 
? A medium which does not allow anydight to pass tough it, is called an opaque 
medium. Examples: wood, metals etc. 
? Light travels in a straight line path. This is called the rectilinear propagation of 
light. 
? The pin hole camera is a simple application of the rectilinear propa – gation of 
light. 
? The image (or picture) formed in a pin hole camera is upside down (i.e. inverted). 
On increasing the distance of screen from the pin hole, the size of image 
increases. 
? The shadow of an opaque object is the dark patch obtained on the screen when 
that opaque object is placed in the path of light. 
? Shadow is formed because light travels in a straight line path. 
? The shadow is similar to the shape of the object. 
? The part of the shadow where no light reaches from the source is completely dark 
and is called the umbra. 
? The part of the shadow where light reaches from only a portion of the source is 
partially dark and is called the penumbra. 
? There is only umbra in the shadow of an opaque object due to a point source. The 
umbra is bigger in size than that of the obj ect. The umbra increases in size if the 
screen is moved away from the object. 
? The shadow of an object due to a light source smaller than the object contains an 
umbra surrounded by a penumbra. The umbra is bigger in size than that of the 
object. Both the umbra and penum¬bra increase in size as the screen is moved 
away from the source. 
? The shadow of an opaque object due to a light source bigger than the object 
contains an umbra (which is much smaller in size than the object) surrounded by a 
Page 2


? Synposis 
? Light itself is not visible, but in the presence of light other objects become visible 
A. 
? Light is defined as the external physical cause that affects the eye to produce the 
sensation of vision. 
? Two types of sources of light are: 
(1) Natural sources such as sun, stars andjugnu. 
(2) Artificial sources such as fire, electric lamp, electric tube light, a burning 
candle, a kerosene lamps heated bodies, etc. 
? The bodies which themselves emit light are called luminous bodies. Examples: 
torch, electric lamps electric tube light, burning candle, kerosene lamp, sun, stars. 
Jugnu etc. 
? The bodies which do not emit light by their own, but they become visible because 
of the light falling on them from a luminous body, are called non-luminous bodies. 
Examples: moon, earth, table, book, chair etc. 
? A medium which allows the passage of light through it easily, is called a 
transparent medium. Examples: glass, air, water etc. 
? A medium which allows only a small amount oflight to pass through it, is called a 
translucent medium. Examples: ground glass, tracing paper etc. 
? A medium which does not allow anydight to pass tough it, is called an opaque 
medium. Examples: wood, metals etc. 
? Light travels in a straight line path. This is called the rectilinear propagation of 
light. 
? The pin hole camera is a simple application of the rectilinear propa – gation of 
light. 
? The image (or picture) formed in a pin hole camera is upside down (i.e. inverted). 
On increasing the distance of screen from the pin hole, the size of image 
increases. 
? The shadow of an opaque object is the dark patch obtained on the screen when 
that opaque object is placed in the path of light. 
? Shadow is formed because light travels in a straight line path. 
? The shadow is similar to the shape of the object. 
? The part of the shadow where no light reaches from the source is completely dark 
and is called the umbra. 
? The part of the shadow where light reaches from only a portion of the source is 
partially dark and is called the penumbra. 
? There is only umbra in the shadow of an opaque object due to a point source. The 
umbra is bigger in size than that of the obj ect. The umbra increases in size if the 
screen is moved away from the object. 
? The shadow of an object due to a light source smaller than the object contains an 
umbra surrounded by a penumbra. The umbra is bigger in size than that of the 
object. Both the umbra and penum¬bra increase in size as the screen is moved 
away from the source. 
? The shadow of an opaque object due to a light source bigger than the object 
contains an umbra (which is much smaller in size than the object) surrounded by a 
penumbra. The umbra diminishes while the penumbra increases in size if the 
screen is moved away from the object. 
? Lunar and solar eclipses are the examples of formation of shadows in nature. 
? A lunar eclipse is caused on a certain full moon night when the earth comes in 
between the sun and the moon so that the earth casts its shadow on the moon. 
? A solar eclipse is caused on a certain new moon’s day when the moon comes in 
between the sun and the earth so that the moon casts its shadow 
Test yourself 
A. Short Answer Questions 
1. Write true or false for each statement 
(a) The moon is a natural source of light. 
Answer. False 
(b) The moon is self luminous. 
Answer. False 
(c) We can see an object through an opaque medium. 
Answer. False 
(d) Light passes through glass. 
Answer. True 
(e) Light travels in a straight line path. . 
Answer. True 
(f) Image formed in a pin hole camera is real. 
Answer. True 
(g) The image in a pin hole camera gets blurred if the hole is made bigger. 
Answer. True 
(h) A shadow is formed because light travels in a straight line path. 
Answer. True 
(i) Solar eclipse occurs when the sun comes in between the earth and the moon. 
Answer. False 
Page 3


? Synposis 
? Light itself is not visible, but in the presence of light other objects become visible 
A. 
? Light is defined as the external physical cause that affects the eye to produce the 
sensation of vision. 
? Two types of sources of light are: 
(1) Natural sources such as sun, stars andjugnu. 
(2) Artificial sources such as fire, electric lamp, electric tube light, a burning 
candle, a kerosene lamps heated bodies, etc. 
? The bodies which themselves emit light are called luminous bodies. Examples: 
torch, electric lamps electric tube light, burning candle, kerosene lamp, sun, stars. 
Jugnu etc. 
? The bodies which do not emit light by their own, but they become visible because 
of the light falling on them from a luminous body, are called non-luminous bodies. 
Examples: moon, earth, table, book, chair etc. 
? A medium which allows the passage of light through it easily, is called a 
transparent medium. Examples: glass, air, water etc. 
? A medium which allows only a small amount oflight to pass through it, is called a 
translucent medium. Examples: ground glass, tracing paper etc. 
? A medium which does not allow anydight to pass tough it, is called an opaque 
medium. Examples: wood, metals etc. 
? Light travels in a straight line path. This is called the rectilinear propagation of 
light. 
? The pin hole camera is a simple application of the rectilinear propa – gation of 
light. 
? The image (or picture) formed in a pin hole camera is upside down (i.e. inverted). 
On increasing the distance of screen from the pin hole, the size of image 
increases. 
? The shadow of an opaque object is the dark patch obtained on the screen when 
that opaque object is placed in the path of light. 
? Shadow is formed because light travels in a straight line path. 
? The shadow is similar to the shape of the object. 
? The part of the shadow where no light reaches from the source is completely dark 
and is called the umbra. 
? The part of the shadow where light reaches from only a portion of the source is 
partially dark and is called the penumbra. 
? There is only umbra in the shadow of an opaque object due to a point source. The 
umbra is bigger in size than that of the obj ect. The umbra increases in size if the 
screen is moved away from the object. 
? The shadow of an object due to a light source smaller than the object contains an 
umbra surrounded by a penumbra. The umbra is bigger in size than that of the 
object. Both the umbra and penum¬bra increase in size as the screen is moved 
away from the source. 
? The shadow of an opaque object due to a light source bigger than the object 
contains an umbra (which is much smaller in size than the object) surrounded by a 
penumbra. The umbra diminishes while the penumbra increases in size if the 
screen is moved away from the object. 
? Lunar and solar eclipses are the examples of formation of shadows in nature. 
? A lunar eclipse is caused on a certain full moon night when the earth comes in 
between the sun and the moon so that the earth casts its shadow on the moon. 
? A solar eclipse is caused on a certain new moon’s day when the moon comes in 
between the sun and the earth so that the moon casts its shadow 
Test yourself 
A. Short Answer Questions 
1. Write true or false for each statement 
(a) The moon is a natural source of light. 
Answer. False 
(b) The moon is self luminous. 
Answer. False 
(c) We can see an object through an opaque medium. 
Answer. False 
(d) Light passes through glass. 
Answer. True 
(e) Light travels in a straight line path. . 
Answer. True 
(f) Image formed in a pin hole camera is real. 
Answer. True 
(g) The image in a pin hole camera gets blurred if the hole is made bigger. 
Answer. True 
(h) A shadow is formed because light travels in a straight line path. 
Answer. True 
(i) Solar eclipse occurs when the sun comes in between the earth and the moon. 
Answer. False 
(j) If the shadow of earth falls on the moon, the eclipse is called the lunar eclipse. 
Answer. True 
2. Fill in the blanks 
(a) Light gives us the sensation of vision. 
(b) The sun is a natural source of light. 
(c) A medium through which light cannot pass is called the opaque medium. 
(d) A medium which allows light to pass through it easily is called the transparent 
medium. 
(e) Moon is a non-luminous body. 
(f) Light travels in a straight line path. 
(g) In a pin hole camera, the image formed is inverted and real. 
(h) The darkest portion of a shadow is called the umbra. 
(i) The less dark portion of a shadow is called the penumbra. 
(j) Lunar eclipse occurs when the earth comes in between the moon and the sun. 
3. Match the following columns 
 
 
4. Select the correct alternative 
(i) The natural source of light is 
1. candle flame 
Page 4


? Synposis 
? Light itself is not visible, but in the presence of light other objects become visible 
A. 
? Light is defined as the external physical cause that affects the eye to produce the 
sensation of vision. 
? Two types of sources of light are: 
(1) Natural sources such as sun, stars andjugnu. 
(2) Artificial sources such as fire, electric lamp, electric tube light, a burning 
candle, a kerosene lamps heated bodies, etc. 
? The bodies which themselves emit light are called luminous bodies. Examples: 
torch, electric lamps electric tube light, burning candle, kerosene lamp, sun, stars. 
Jugnu etc. 
? The bodies which do not emit light by their own, but they become visible because 
of the light falling on them from a luminous body, are called non-luminous bodies. 
Examples: moon, earth, table, book, chair etc. 
? A medium which allows the passage of light through it easily, is called a 
transparent medium. Examples: glass, air, water etc. 
? A medium which allows only a small amount oflight to pass through it, is called a 
translucent medium. Examples: ground glass, tracing paper etc. 
? A medium which does not allow anydight to pass tough it, is called an opaque 
medium. Examples: wood, metals etc. 
? Light travels in a straight line path. This is called the rectilinear propagation of 
light. 
? The pin hole camera is a simple application of the rectilinear propa – gation of 
light. 
? The image (or picture) formed in a pin hole camera is upside down (i.e. inverted). 
On increasing the distance of screen from the pin hole, the size of image 
increases. 
? The shadow of an opaque object is the dark patch obtained on the screen when 
that opaque object is placed in the path of light. 
? Shadow is formed because light travels in a straight line path. 
? The shadow is similar to the shape of the object. 
? The part of the shadow where no light reaches from the source is completely dark 
and is called the umbra. 
? The part of the shadow where light reaches from only a portion of the source is 
partially dark and is called the penumbra. 
? There is only umbra in the shadow of an opaque object due to a point source. The 
umbra is bigger in size than that of the obj ect. The umbra increases in size if the 
screen is moved away from the object. 
? The shadow of an object due to a light source smaller than the object contains an 
umbra surrounded by a penumbra. The umbra is bigger in size than that of the 
object. Both the umbra and penum¬bra increase in size as the screen is moved 
away from the source. 
? The shadow of an opaque object due to a light source bigger than the object 
contains an umbra (which is much smaller in size than the object) surrounded by a 
penumbra. The umbra diminishes while the penumbra increases in size if the 
screen is moved away from the object. 
? Lunar and solar eclipses are the examples of formation of shadows in nature. 
? A lunar eclipse is caused on a certain full moon night when the earth comes in 
between the sun and the moon so that the earth casts its shadow on the moon. 
? A solar eclipse is caused on a certain new moon’s day when the moon comes in 
between the sun and the earth so that the moon casts its shadow 
Test yourself 
A. Short Answer Questions 
1. Write true or false for each statement 
(a) The moon is a natural source of light. 
Answer. False 
(b) The moon is self luminous. 
Answer. False 
(c) We can see an object through an opaque medium. 
Answer. False 
(d) Light passes through glass. 
Answer. True 
(e) Light travels in a straight line path. . 
Answer. True 
(f) Image formed in a pin hole camera is real. 
Answer. True 
(g) The image in a pin hole camera gets blurred if the hole is made bigger. 
Answer. True 
(h) A shadow is formed because light travels in a straight line path. 
Answer. True 
(i) Solar eclipse occurs when the sun comes in between the earth and the moon. 
Answer. False 
(j) If the shadow of earth falls on the moon, the eclipse is called the lunar eclipse. 
Answer. True 
2. Fill in the blanks 
(a) Light gives us the sensation of vision. 
(b) The sun is a natural source of light. 
(c) A medium through which light cannot pass is called the opaque medium. 
(d) A medium which allows light to pass through it easily is called the transparent 
medium. 
(e) Moon is a non-luminous body. 
(f) Light travels in a straight line path. 
(g) In a pin hole camera, the image formed is inverted and real. 
(h) The darkest portion of a shadow is called the umbra. 
(i) The less dark portion of a shadow is called the penumbra. 
(j) Lunar eclipse occurs when the earth comes in between the moon and the sun. 
3. Match the following columns 
 
 
4. Select the correct alternative 
(i) The natural source of light is 
1. candle flame 
2. electric lamp 
3. sun 
4. kerosene lamp 
(ii) The formation of inverted image in a pin hole camera shows that 
1. light enables us to see 
2. light travels in a straight line path 
3. light can pass through the pin hole 
4. light does not pass through the pin hole 
(iii) The luminous body is 
1. a lighted bulb 
2. earth 
3. noon 
4. table 
(iv) Umbra is a region of 
1. complete darkness 
2. partial darkness 
3. complete brightness 
4. partial brightness 
(v) Penumbra is a region of 
1. complete darkness 
2. complete brightness 
3. partial brightness 
4. none of the above 
(vi) Solar eclipse occurs on 
1. every new moon’s day 
2. certain new moon’s day 
3. every full moon’s day 
4. certain full moon’s day 
(vii) Lunar eclipse occurs on 
1. every full moon’s night 
2. certain full moon’s night 
3. every new moon’s day 
Page 5


? Synposis 
? Light itself is not visible, but in the presence of light other objects become visible 
A. 
? Light is defined as the external physical cause that affects the eye to produce the 
sensation of vision. 
? Two types of sources of light are: 
(1) Natural sources such as sun, stars andjugnu. 
(2) Artificial sources such as fire, electric lamp, electric tube light, a burning 
candle, a kerosene lamps heated bodies, etc. 
? The bodies which themselves emit light are called luminous bodies. Examples: 
torch, electric lamps electric tube light, burning candle, kerosene lamp, sun, stars. 
Jugnu etc. 
? The bodies which do not emit light by their own, but they become visible because 
of the light falling on them from a luminous body, are called non-luminous bodies. 
Examples: moon, earth, table, book, chair etc. 
? A medium which allows the passage of light through it easily, is called a 
transparent medium. Examples: glass, air, water etc. 
? A medium which allows only a small amount oflight to pass through it, is called a 
translucent medium. Examples: ground glass, tracing paper etc. 
? A medium which does not allow anydight to pass tough it, is called an opaque 
medium. Examples: wood, metals etc. 
? Light travels in a straight line path. This is called the rectilinear propagation of 
light. 
? The pin hole camera is a simple application of the rectilinear propa – gation of 
light. 
? The image (or picture) formed in a pin hole camera is upside down (i.e. inverted). 
On increasing the distance of screen from the pin hole, the size of image 
increases. 
? The shadow of an opaque object is the dark patch obtained on the screen when 
that opaque object is placed in the path of light. 
? Shadow is formed because light travels in a straight line path. 
? The shadow is similar to the shape of the object. 
? The part of the shadow where no light reaches from the source is completely dark 
and is called the umbra. 
? The part of the shadow where light reaches from only a portion of the source is 
partially dark and is called the penumbra. 
? There is only umbra in the shadow of an opaque object due to a point source. The 
umbra is bigger in size than that of the obj ect. The umbra increases in size if the 
screen is moved away from the object. 
? The shadow of an object due to a light source smaller than the object contains an 
umbra surrounded by a penumbra. The umbra is bigger in size than that of the 
object. Both the umbra and penum¬bra increase in size as the screen is moved 
away from the source. 
? The shadow of an opaque object due to a light source bigger than the object 
contains an umbra (which is much smaller in size than the object) surrounded by a 
penumbra. The umbra diminishes while the penumbra increases in size if the 
screen is moved away from the object. 
? Lunar and solar eclipses are the examples of formation of shadows in nature. 
? A lunar eclipse is caused on a certain full moon night when the earth comes in 
between the sun and the moon so that the earth casts its shadow on the moon. 
? A solar eclipse is caused on a certain new moon’s day when the moon comes in 
between the sun and the earth so that the moon casts its shadow 
Test yourself 
A. Short Answer Questions 
1. Write true or false for each statement 
(a) The moon is a natural source of light. 
Answer. False 
(b) The moon is self luminous. 
Answer. False 
(c) We can see an object through an opaque medium. 
Answer. False 
(d) Light passes through glass. 
Answer. True 
(e) Light travels in a straight line path. . 
Answer. True 
(f) Image formed in a pin hole camera is real. 
Answer. True 
(g) The image in a pin hole camera gets blurred if the hole is made bigger. 
Answer. True 
(h) A shadow is formed because light travels in a straight line path. 
Answer. True 
(i) Solar eclipse occurs when the sun comes in between the earth and the moon. 
Answer. False 
(j) If the shadow of earth falls on the moon, the eclipse is called the lunar eclipse. 
Answer. True 
2. Fill in the blanks 
(a) Light gives us the sensation of vision. 
(b) The sun is a natural source of light. 
(c) A medium through which light cannot pass is called the opaque medium. 
(d) A medium which allows light to pass through it easily is called the transparent 
medium. 
(e) Moon is a non-luminous body. 
(f) Light travels in a straight line path. 
(g) In a pin hole camera, the image formed is inverted and real. 
(h) The darkest portion of a shadow is called the umbra. 
(i) The less dark portion of a shadow is called the penumbra. 
(j) Lunar eclipse occurs when the earth comes in between the moon and the sun. 
3. Match the following columns 
 
 
4. Select the correct alternative 
(i) The natural source of light is 
1. candle flame 
2. electric lamp 
3. sun 
4. kerosene lamp 
(ii) The formation of inverted image in a pin hole camera shows that 
1. light enables us to see 
2. light travels in a straight line path 
3. light can pass through the pin hole 
4. light does not pass through the pin hole 
(iii) The luminous body is 
1. a lighted bulb 
2. earth 
3. noon 
4. table 
(iv) Umbra is a region of 
1. complete darkness 
2. partial darkness 
3. complete brightness 
4. partial brightness 
(v) Penumbra is a region of 
1. complete darkness 
2. complete brightness 
3. partial brightness 
4. none of the above 
(vi) Solar eclipse occurs on 
1. every new moon’s day 
2. certain new moon’s day 
3. every full moon’s day 
4. certain full moon’s day 
(vii) Lunar eclipse occurs on 
1. every full moon’s night 
2. certain full moon’s night 
3. every new moon’s day 
4. certain new moon’s day 
B. Short/Long Answer Questions 
Question 1. 
What is light ? Define it. 
Answer: 
Light is a form of Energy i. e. The external physical cause that affects our eye to 
produce the sensation of vision. 
Question 2. 
How does light make an object visible ? 
Answer: 
An object becomes visible to us when the light after striking the object reaches our 
eyes. Light itself is not visible, but light makes objects visible to us. 
Question 3. 
Name two natural sources of light. 
Answer: 
Sun, stars,jugnu, firefly. 
Question 4. 
List two artificial sources of light. 
Answer: 
Electric bulb, torch, an oil lamp, fluorescent tube, candle. 
Question 5. 
Differentiate between the luminous and non-luminous bodies. Give two examples of 
each. 
Answer: 
Difference Between 
Luminous 
The bodies which have light of their own e.g. sun stars, bulb, candle, oil lamp, torch, a 
lantern. 
Non-Luminous 
The bodies-which do not have their own Iight.e.g. moon, chair, table. When light falls on 
them, they become visible. 
Question 6. 
Is the moon a luminous object ? 
Answer: 
Moon is not a luminous body, it is nbn-luminous body. It has no light of its own.