14 – Light and The Formation of Shadows
Q. 1. Choose an appropriate word and fill in the
blanks :
(seven, star, through, transparent, opaque,
colours, shape, erect, inverted, lumina candle)
(1) A …….....
is a natural source of light.
(2) A …………… is an artificial source of light.
(3) When a light passes through a prism, it gets
separated into ……………. Colours.
(4) The image obtained in the pinhole camera
is...................
(5) A
shadow is formed when an……….. object comes in the way of light
(6) When
a ………….object comes in the way of light, light passes …………… it
Ans. (1) A star is a natural source of light.
(2) A
candle is an artificial source of light.
(3)
When a light passes through a prism. it gets separated into seven colours.
(4)
The image obtained in the pinhole camera is inverted
(5) A
shadow is formed when an opaque object comes in the way of light
(6)
When a transparent object comes in the way of light, light passes through it.
Q. 2.
Write whether the following objects are luminous or non-luminous.
Ans.
Object Luminous
/ non-luminous Non-luminous
A book Non-luminous
A burning candle Luminous
A wax cloth Non-luminous
A pencil
Non-luminous
A pen Non-luminous
A light bulb
Luminous
A tyre Non-Luminous
A torch Luminous
Q.
3. Match the columns :
Ans
(1) Mirror – Reflection
(2) Firefly – Luminous
(3) Pinhole camera - Inverted image
(4) Moon - Non-luminous
Q. 4. Write the answers to the
following:
(1)
When can an object be seen ?
Ans.
The light rays from the source of the light, fall on an object. When this light
reflects from the surface of the object, it enters our eyes. Therefore, we are
able to see this object. The luminous objects can be seen as they emit their
own light.
(2) What is a shadow ?
Ans.
Shadow is produced by an opaque object. Light does not pass through an opaque
object. It does not reach the wall or any other
surface on the other side of the object. This part therefore remains dark. This
dark area is called the shadow of that object.
(3)
What things are necessary for the formation of a shadow ?
Ans.
The following things are necessary for the formation of a shadow. The source of
light, an opaque object and a surface on which the shadow falls.
