The dark
coloured patch formed on the screen opposite to the light by an opaque object is
called shadow. For the formation of a shadow, a source of light, an opaque
object and a screen are required. Shadow is formed by an opaque object when
light falls on it. Its size and shape change according to direction of light or
orientation of object. It can be large or small than the object. During morning
and evening shadow is larger. It is smaller during noon. The colour of shadow
is dark irrespective of the colour of object. Shadows are not formed in dark
i.e. in absence of light. The shadows are not uniformly dark. Central inner
part is darker than outer surrounding part. The darker part of shadow is called
umbra and less dark part is called penumbra. There is no change of left
part of object to right part of image and right part of object to left part of
image.
In nature,
lunar eclipse and solar eclipses are examples of shadow formation.
Q.1 Among the followings options
which is not always necessary for shadow formation?1
(a) The sun
(b) A screen
(c) An Opaque object
(d) A source of light
Q.2 Harshit
observed his shadow at 9:00 A.M., 12:00 Noon and 3:00 P.M. Which among the following statements is correct about
his observation of shadow? 1
(a) His shape
changes but size remains same.
(b) His size
changes but shape remains same.
(c) Both
shape and size of his shadow change.
(d) Neither
shape nor size of his shadow change.
Q.3 Four
shirts of red, blue, green and yellow colour are hanging on a clothes line in
the sun. What will be the colour of their shadows? 1
(a) Their
shadows will be red, blue, green and yellow.
(b) Their
shadows will be light dark in colour.
(c) Their
shadows will be light red in the sunlight.
(d) Their
shadows will be purple in colour.
Q.4 Which
of the following statements is true about umbra and penumbra of a shadow? 1
(a) Umbra
is comparatively darker than penumbra
(b)
Penumbra is comparatively darker than umbra
(c) Umbra
is same as penumbra in darkness.
(d) Umbra
is comparatively lighter than penumbra.
Q.5 In an
activity four torches A, B, C and D were switched on an apple. Looking their position
which position, which torch or torches will not form their shadow on the
screen? 1
(a) Torch A
(b) Torch C
(c) Torch D
(d)
Both Torch C and D
Q.6 Which
among the following objects will never form a circular shadow? 1
(a) A football
(b) A flat circular disc
(c) A cylindrical metal rod
(d) A rectangular
box
Q.7 What
will be the conditions of formation of Solar eclipse? 2
Ans.-1 (a)
The sun
Ans.-2 (c)
Both shape and size of his shadow change.
Ans.-3 (b)
Their shadows will be light dark in colour.
Ans.-4 (a)
Umbra is comparatively darker than penumbra
Ans.-5 (d)
Both Torch C and D
Ans.-6 When
the Moon comes in between the Sun and the Earth in a straight pathway, solar
eclipse is formed.
No comments:
Post a Comment