NCERT Solutions Curiosity Chapter 11 .4 Shadow Formation — Activity 11.4: Let us explore
Book page 15811 Updated on2026-09-05
Q1.
Did the shadow form in all cases? Was the shape and size of the shadow the same as the object? Record your observations in the second column of Table 11.2.
Answer
No, a shadow was not formed in every case — three of the seven actions destroy the shadow altogether. And the shadow is hardly ever exactly the same size as the object; it is usually bigger, and it keeps the object's outline only when the object faces the light squarely.
Action
Observations regarding shadow
The screen is removed.
No shadow is seen. The light simply travels on into the room; with nothing to catch it, there is nothing on which the dark patch can appear.
The object is removed.
No shadow. The screen shows only a bright circle of torch light.
The torch is switched off.
No shadow — there is no light to be blocked.
The object is moved closer to the screen, keeping the torch and the screen fixed.
The shadow becomes smaller and its edges become sharper. Its size comes close to the size of the object.
The object is moved closer to the torch, keeping the torch and the screen fixed.
The shadow becomes larger and its edges become blurred.
The object is tilted, keeping the torch and the screen fixed.
The shape of the shadow changes. A round disc, for example, gives a circle when it faces the torch, an oval when it is tilted, and almost a straight line when its edge faces the torch.
The colour of the object is changed.
No change at all. The shadow stays dark, of the same shape and size. A red ball and a green ball of the same size cast exactly the same shadow.
The rays spread out from the torch. An object placed near the torch cuts off a wide cone of light, so its shadow on the wall is large; the same object near the wall cuts off only a narrow cone, so its shadow is small.
Q2.
What conclusions do you draw from this activity? What do we need to observe a shadow? Does the colour of the shadow change when the colour of the object is changed?
Answer
Three things are needed to observe a shadow:
a source of light + an opaque object + a screen → shadow
Take away any one of the three and the shadow disappears. In everyday life the wall, the floor, the ground or any other surface acts as the screen.
No — the colour of the shadow does not change when the colour of the object is changed. The shadow of a red ball and of a blue ball is the same dark patch.
Why it happens: A shadow is not made of the object; it is only the region where the object's body has stopped the light from reaching the screen. Since “no light” has no colour, the shadow is simply dark, whatever colour the object may be. The shape, size and sharpness of a shadow depend on where the object stands with respect to the light source and the screen, not on its colour.
Try This: Cover the torch face with a red transparent sheet. Now the lit part of the wall turns red, but the shadow is still a dark patch — the colour came from the light, not from the object.