Light Sources - Natural Light Sources, Artificial Light Sources, FAQs

What is Light?

Light is a form of energy that allows us to see. Light moves in a straight line and can travel through air, water, and empty space. In the absence of light, everything would be dark, and our eyes would not be able to perceive it. The Sun is the main natural source of light. Light enables us to see colour, shape, and objects near us. It also helps the plants prepare their food through the process of photosynthesis.

Properties of Light

• It is a non-mechanical wave as it doesn't require any medium to travel.
• Visible light (that enables us to see) has a very small wavelength i.e., it lies in the range of $400-700 \mathrm{~nm}$.
• Speed of light in vacuum is $299,792,458 \mathrm{~m} / \mathrm{s}$ (approx. $3 \times 10^8 \mathrm{~m} / \mathrm{s}$ ).
• It is a transverse, electromagnetic wave.

Types of Light Source

Light sources can be grouped into two main types, which are natural and artificial light sources.

Natural Light Sources – Definition and Examples

Natural light sources arise in nature and are not made by human beings. These sources generate light by themselves without any support from electricity or fuels. Natural light is predominantly available during the day, while some sources may be seen at night.

Examples of Natural Light Sources

• Sun – The primary and most powerful source of light on Earth. It gives us daylight and energy.
• Stars – They appear as tiny dots of light in the night sky. They are, in fact, huge spheres of burning gases far away.
• Fire –Natural fire from wood or grass burning also produces some light.
• Lightning – It is a flash in the atmosphere during storms created by an electric discharge.
• Fireflies – The insects that glow through bioluminescence, a natural chemical process.
• Lava – The hot, glowing liquid rock from volcanically active regions can emit light.
• Some sea creatures – Deep-sea creatures like jellyfish can glow in the dark using bioluminescence as well.

Artificial Light Sources – Meaning and Examples

Artificial light sources are man-made. They were developed to bring illumination when natural light is not enogh, particularly at night or dark areas. These source use electricity, chemicals, or fuels to produce light.

Examples of Artificial Light Sources

• Electric bulb – The most common source of light used in homes and schools that works with electricity.
• Tube lights – Long lights to illuminate rooms and halls.
• LEDs – Light-emitting diodes that consume less energy and last for a long time.
• Candle – An ancient way of producing light, burning wax.
• Oil lamp – It burns oil and produces light; it is commonly used in villages.
• Laser lights – A focused beam of light, used in machines, shows, or surgeries.
• Mobile flashlight – A small LED torch attached to mobile phones for emergency work.

Do you know?

How fast does light travel?
About 186,000 miles per second $(300,000 \mathrm{~km} / \mathrm{s})$, so light from the sun takes about 8 minutes 20 second to travel 93 million miles ( 149 million km ) to reach earth. If you drive to the sun at $60 \mathrm{mph}(100 \mathrm{~km} / \mathrm{h})$, it would take you 171.2 years to reach there.

Difference Between Natural and Artificial Light Sources

Table below is showing the diffrence between nagtural and artificial source of light.

Fun Facts About Light

• It travels at a speed of 300,000 kilometres per second in space.
• Sunlight takes approximately 8 minutes to reach the surface of the Earth.
• The Moon does not emit its own light but only reflects the light coming from the Sun.
• Fireflies and some other sea creatures have the ability to emit light naturally; the property by which this is achieved is called bioluminescence.
• The colours of white light consist of seven distinct colours, which you see in a rainbow.
• Light travels in a straight line unless it is bent by something, such as water or a lens.
• LED lights have a longer life and consume less power as compared to incandescent bulbs.