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๐ฌ Think about it
The Sun, a flame, lightning, even a firefly — all give out their own light. But the Moon, a book, a wall do not. So how do we sort things into those that shine on their own and those that only borrow light? Let us find out.
What are luminous and non-luminous objects?
- The Sun gives out its own light and is our main natural source.
- Stars, lightning, fire, and some animals also emit light.
- Objects that emit their own light are called luminous objects.
- Objects that do not emit light are called non-luminous objects.
Example:
The Moon is a non-luminous object — it does not make its own light, it only reflects the Sun's light.
Luminous objects
Non-luminous objects
Emit their own light
Do not emit their own light
Sun, stars, fire, fireflies
Moon, book, wall
Can be seen on their own
Seen by reflected light
How did human lighting change over time?
- In ancient times, humans learnt to create fire.
- Fire was the earliest form of artificial lighting.
- They made fire using fuels like animal fat, oil, wax, and gas.
- Today most lighting needs are met by electric lights.
Example:
An oil lamp (diya) is an old artificial light, while an LED bulb is a modern electric one.
๐ก๏ธ Science and Society
- LED lamps are modern lights that use much less power.
- They are brighter and last longer than traditional lamps.
- This lowers electricity bills and is better for the environment.
- The Indian government promotes LED lamps across the country.
- At their end of life, LED lamps must be recycled, not thrown away.
Important Points
- Luminous objects make their own light.
- Non-luminous objects only reflect light.
- The Moon is non-luminous.
โ Test Yourself
-
What is a luminous object?
View Answer
An object that emits its own light, like the Sun. -
What is a non-luminous object?
View Answer
An object that does not emit its own light, like the Moon. -
Why is the Moon non-luminous?
View Answer
It does not make light; it only reflects the Sun's light. -
What was the earliest form of artificial light?
View Answer
Fire. -
Why are LED lamps good for the environment?
View Answer
They use much less power and last longer.
Important Definitions
- Luminous objects — objects that emit their own light, like the Sun, stars, and fire.
- Non-luminous objects — objects that do not emit their own light, like the Moon.
๐ NCERT Question 1 — Which of the following are
Which of the following are luminous objects? Mars, Moon, Pole Star, Sun, Venus, Mirror.
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