Light enables us to see objects and enables vision. Objects are classified as opaque, translucent, or transparent based on how much light they allow to pass through. A shadow is formed when an opaque or translucent object blocks light from a source, appearing as a dark area on the surface behind the object. The size and shape of a shadow depends on the position of the light source and object.

4. Light
• Light is a form of energy which is
responsible for the sense of sight . It
enables to see things around us.
• Light enables us to see every object around
us like trees, vehicles, houses, people, etc.
• At night due to the absence of sunlight, it
becomes dark, which reduces our visibility.

5. • Objects that emit light are called
like sun, bulb, tube light.
• Any non-light emitting object is visible when light
from a luminous source falls on that object and
then reaches our eye . These objects are called
like trees, animals, shoe, moon
(it seems glowing because of sun’s light falling on
it) etc.

6. •Objects are classified
based on amount of
light that can pass
through them.

7. Opaque Translucent Transparen
t
These objects do
not allow light to
pass through them.
These objects allow light
to pass through them
partially.
These objects allow
light to pass through
them completely.
We can’t see
through these
objects.
We can see through these
objects a little but not
clearly.
We can see through
these objects clearly.
Examples wall, door,
trees etc.
Examples polythene,
butter paper, thin plastic
sheet etc.
Examples air, water, clear
glass, etc.

9. • A shadow is a space where light from a
light source is blocked by an opaque
object.
• A shadow is formed when a part of light
is blocked by the object.
• If all the light is blocked by an object,
then there will not be any shadow.
• Shape of the shadow is always similar
to that of the object but the size varies.

10. • When it translucent or an opaque
object is placed before a source of
light ,a dark spot forms on the
opposite side of the light .
• The dark spot formed by a
translucent or an opaque object
when it blocks the light is called a
shadow .

11. SHADOWS AND TYPE OF OBJECTS
1. Transparent objects do not
form shadows as they do not
block light .
2. Translucent object forms light
shadow as they partially blocks
the light .
3. Opaque object forms dark
shadow as they completely
blocks the light .

12. 1. A source of light
2. A translucent or an opaque object
3. A surface (screen) on which the shadow can be
formed

13. 1. A shadow is formed on the opposite side
of the light source .
2. A shadow is black even when the object is
of any other color .
3. A shadow shows only the shape or outline
of the object , not the details .
4. The size of the shadow depends on the
distance between the object and a source
of light . it also depends on the distance
between the object and the surface where
it formed .

14. • Shadows formed by the sun are shortest at noon
because the size of the shadow depends on the
distance between the object, the surface where it
formed and the source of light . At noon, the sun
is directly overhead (sun is near to earth compared
to mornings and evenings). so the rays fall
vertically on the object. So Shortest shadow is at
noon.

15. The shadow is longest in the
morning and evening because
in mornings and evenings, the
sun rays fall at an inclined
position. i.e. sun is far away
from earth in the morning
and evening.

16. Shadows cannot occur in
dark rooms due to absence
of light and full lit rooms
with no objects due to
absence of opaque object.
• A shadow is always
obtained on a screen like
walls, ground etc.
• A shadow is always
black or grey irrespective
of the colour of the
object.

17. 1. https://youtu.be/WNKIdIE4Aec?list=PLHOGBLPrsnMox
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4. https://youtu.be/P6Uihn8V3h4?list=PLHOGBLPrsnMox4
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5. https://youtu.be/V6pjHnA39CQ?list=PLHOGBLPrsnMox
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6. https://youtu.be/DavnmxgVwaw?list=PLHOGBLPrsnMo
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7. https://youtu.be/OAgRTdIgZGs?list=PLHOGBLPrsnMox4
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8. https://youtu.be/yd5WRAgl1cQ