Chapter 14 - Light and the Formation of Shadows
1. Choose an appropriate word and fill in the blanks.
(a) A ……….. is a natural source of light.
Ans: star
(b) A ……… is an artificial source of light.
Ans: candle
(c) When light passes through a prism, it gets separated into ……. colours.
Ans: seven
(d) The image obtained in the pinhole camera is ……… .
Ans: inverted
(e) A shadow is formed when an ……….. object comes in the way of light.
Ans: opaque
(f) When a ……….. object comes in the way of light, light passes ……… it.
Ans: transparent
(seven, star, through, transparent, opaque, colors, shape, erect, inverted, luminous, candle)
2. Write whether of the following objects are luminous or non-luminous.
| Object | Luminous/ Non-luminous |
|---|---|
A book | |
A burning candle | |
A wax cloth | |
A pencil | |
A pen | |
A light bulb | |
A tyre | |
A torch |
Ans:
| Object | 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 |
3. Match the following.
| Group A | Group B |
|---|---|
(a) Mirror | (1) Non-luminous |
(b) Firefly | (2) Inverted image |
(c) Pinhole camera | (3) Reflection |
(d) Moon | (4) Luminous |
Ans:
| Group A | Group B |
|---|---|
(a) Mirror | (3) Reflection |
(b) Firefly | (4) Luminous |
(c) Pinhole camera | (2) Inverted image |
(d) Moon | (1) Non-luminous |
4. Write the answers to the following.
(a) What things are necessary for the formation of a shadow?
Ans: The things necessary for the formation of a shadow are:
(i) A source of light,
(ii) An opaque object whose shadow has to be formed,
(iii) A screen on which a shadow is to be formed.
(b) When can an object be seen?
Ans: The rays of light falling on an object from a source of light are thrown back from the surface of that object. We see the object when the reflected rays reach and enter our eyes.
(c) What is a shadow?
Ans: A shadow is a dark patch obtained on a screen where the light from a light source is blocked by an opaque object.