Page 110 - Viva ICSE Science 5 : E-book

Conditions for the formation of a shadow

A shadow is formed when the path of light is
obstructed by an opaque object. A transparent

object does not form a shadow, whereas a
translucent object forms a light shadow. Thus, source of
light
for the formation of a shadow, the following
three things are needed. opaque object a screen

• A source of light Shadow conditions

• An opaque object that comes in the way of the source of light

• A screen or a surface on which the shadow is formed

Characteristic features of the shadow

Shadow shows the following characteristic features.

• Shadow of an object is formed only in the presence of a source of light.

• A shadow is always formed on the opposite side of the source of light. It is a region
without light that forms behind the opaque object.

• The shadow formed is always black in colour. The colour of the shadow does not
change with the change in the colour of opaque object and the colour of light
falling on it.

• The size of the shadow changes depending on the distance between the source of
light and the object. It increases with the decrease in distance and vice versa.

• Position of the shadow changes with the position of the source of light.

Formation of shadow at diff erent times of the day

Shadow of an object is formed only in the morning midday evening
presence of a source of light. Thus, a shadow

cannot be seen in a dark room or during
night as there is no source of light.

During the day, as the source of light, i.e., the
sun moves, the length and the position of

the shadow also changes. It is actually due to
the earth’s rotation that the position of sun
changes throughout the day. Early morning

and during the late afternoon, when the sun

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