Luminous and Non-Luminous Objects

In the basic physics study of 'Light', every single physical object in the universe is divided into two distinct categories based on whether it can produce its own light. These are Luminous and Non-Luminous objects.

Question (Click to Flip)

Is a mirror a luminous object?

Answer

No. A mirror only reflects light. If you put a mirror in a totally dark room without any bulbs, it will be completely dark. Therefore, it is strictly non-luminous.

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Key Facts

A firefly (glow-worm) is a highly rare example of a biological luminous object. It creates cold light inside its body through a massive chemical reaction called Bioluminescence.

1. Luminous Objects

Definition: Objects that physically emit or give out their own massive light energy are called Luminous objects.
Because they create light, we can physically see them even in complete pitch darkness.
Natural Examples: The Sun, distant stars, lightning, and fireflies (Jugnu).
Artificial Examples: A glowing electric bulb, a burning candle, a laser pointer, and a TV screen.

2. Non-Luminous Objects

Definition: Objects that do not produce their own light are called Non-Luminous objects.
How do we see them? We can only see non-luminous objects when light from a luminous object hits them and violently bounces (reflects) into our eyes.
Examples: A wooden table, a plastic chair, human beings, books, and the walls of a room.

3. The Big Question: The Moon

Is the Moon luminous? Absolutely NOT.
The Moon is a giant dead rock in space. It does not create a single drop of light. It beautifully shines at night only because it acts like a massive space mirror, heavily reflecting the bright light of the Sun towards Earth.

Questions and Answers

Is a mirror a luminous object?+

No. A mirror only reflects light. If you put a mirror in a totally dark room without any bulbs, it will be completely dark. Therefore, it is strictly non-luminous.

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