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

Edited By Vishal kumar | Updated on Jul 02, 2025 05:03 PM IST

Everything that we observe in our surroundings is a result of light. Human eyes are sensitive to between 390 and 700 NM, which is a specific frequency of electromagnetic radiation, also known as light. Even when we focus on a single leaf, we are already aware of its green colour since light reflects off of it and reaches our eyes, indicating its colour. In this article of Physics, we will be studying types of light, sources of light, natural sources of light, artificial sources of light, light source, what is a light source, artificial light, point source of light, and examples of natural sources of light.

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

What is Light?

Light exhibits a dual nature. It shows the properties of both waves and particles. According to wave theory, light is made up of a bundle of electromagnetic fields that carry a specific amount of energy.

According to particle theory, light is made up of particles called photons.

Light is basically the visible region of the electromagnetic radiation spectrum, whose wavelength ranges between 400 nm and 700 nm. This spectrum is named as VIBGYOR.

Types of Light Source

We have a lot of sources of light, but all of them can be categorised under two categories.

Natural Light Sources

In simple words, natural light is the light that is generated by a natural source. The universe is filled with numerous sources of light. The emitted light from a few sources of light reaches the Earth. The following natural light sources emit light: The Sun is one of the major sources of light of the earth. Also, the Sun is the main light source for the entire Solar System. In the sun, heat and light are produced by a process called Nuclear Fusion.

Many other stars also produce light, but only a small amount or no amount from them reaches the earth because of the large distance. The moon does not have its own light. So, it reflects the light from the Sun and acts as one of the natural light sources on the Earth.

Bioluminescence - Some living organisms produce light by a chemical reaction that occurs within them.[Another natural light source]
For Example- Fireflies, jellyfish, glowworms, some microorganisms and deep-sea plants.

Volcanic eruptions & Lightning also emit light.

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Examples of natural sources of light or name two natural sources of light- Sun, Stars, etc.

Artificial Light Sources or Man-Made Sources of Light

Apart from natural light sources, there are different artificial light sources that emit light. The different artificial light sources can be put the following categories

Incandescent Sources

When certain objects are heated to a high temperature, they begin to emit both infrared and visible light in the process.

Example- Candles, and incandescent lamps.

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Luminescent Sources

By bypassing current (i.e., by accelerating charges in a luminescent material.) Through the material, light can be produced.

Example- Fluorescent tube light, electric bulb

Gas Discharge Sources

Light can be produced/created by passing electricity across a certain gas at very low pressure.

Example – Neon lamp, Sodium lamp.

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Torch, Candle, Bulb, Lamp, etc. are examples of artificial sources of light.

Also, read

Frequently Asked Questions (FAQs)

1. What are the different types of light sources?

Natural sources & Artificial Sources

2. What are the sources of light energy?

Sun, Flame, Electric Bulb, etc. are the sources of light energy.

3. Distinguish between the natural and artificial sources of light.

Natural light comes from natural sources like the Sun. Whereas artificial light comes from artificial sources like Torch.

4. How many types of light sources are there? And name the two sources of light.

Two types of sources of light-

Natural & Artificial Sources.

Two sources of light-

Sunlight

Fire

5. Name 10 artificial sources of light.

Candle
Lamp
Bulb
Torch
LED’s
Lighter
Fire
Lasers
Flame by matches
Light from TV’s & Phone

These are also known as different types of artificial light.

6. Is the moon a natural source of light?

The moon does not have its own light. So, it reflects the light from the Sun and acts as one of the natural light sources on the Earth.

7. Write the light source definition.

A light source is anything that produces a light. Or we can also say that light originates from light sources.

8. Functions of light in the natural world.

It helps our body to produce Vitamin D, it improves the immune system, sleeps, it even makes us happier.

9. What is the primary difference between natural and artificial light sources?

Natural light sources produce light through natural processes like nuclear fusion or combustion, while artificial light sources are human-made devices that convert other forms of energy into light. For example, the sun is a natural light source, whereas a light bulb is an artificial light source.

10. Can moonlight be considered a natural light source?

Moonlight is not a primary natural light source. The moon itself doesn't produce light; it reflects sunlight. However, it can be considered a secondary natural light source as it provides illumination at night by reflecting the sun's light to Earth.

11. What is the difference between incandescence and luminescence?

Incandescence is light emission from a hot object due to its high temperature, like in traditional light bulbs. Luminescence, on the other hand, is light emission that doesn't result from high temperatures but from electronic excitation, such as in LED lights or bioluminescent organisms.

12. What is the principle behind LED lights?

LED (Light Emitting Diode) lights work on the principle of electroluminescence. When an electric current passes through a semiconductor material, electrons move through the material and fall into lower energy levels, releasing energy in the form of light.

13. How do fluorescent lights work?

Fluorescent lights work by passing an electric current through a gas (usually mercury vapor) to produce ultraviolet light. This ultraviolet light then strikes a phosphor coating on the inside of the tube, causing it to fluoresce and emit visible light.

14. What is the aurora borealis and how does it produce light?

The aurora borealis, or Northern Lights, is a natural light display in Earth's sky. It occurs when charged particles from the sun collide with atoms and molecules in Earth's atmosphere. These collisions excite the atoms, causing them to release energy in the form of colorful light.

15. How does the ozone layer affect natural light reaching Earth's surface?

The ozone layer in Earth's stratosphere absorbs much of the sun's ultraviolet (UV) radiation, particularly UVB rays. This natural "filter" significantly reduces the amount of harmful UV light reaching Earth's surface, protecting life from potential DNA damage. However, it allows visible light and some UVA rays to pass through.

16. What causes the green flash sometimes seen at sunset?

The green flash is a rare optical phenomenon that can occur just as the sun is setting or rising. It happens because Earth's atmosphere acts like a prism, refracting sunlight into its component colors. The blue light is scattered away, leaving the green light visible for a brief moment. This effect is usually only visible under very clear atmospheric conditions and requires an unobstructed view of the horizon.

17. What is the blackbody radiation and how does it relate to light emission?

Blackbody radiation refers to the electromagnetic radiation emitted by an ideal absorber of all wavelengths. As an object's temperature increases, it emits more intense radiation and at shorter wavelengths. This principle explains why heated objects glow, starting from red and progressing to white-hot as temperature increases.

18. What is the phenomenon of triboluminescence?

Triboluminescence is the emission of light when a material is mechanically stressed or broken. It occurs in some crystals and even in everyday items like wintergreen Life Savers candies. When you crush these candies in the dark, you can see a brief flash of light. This happens due to the separation and reunification of electrical charges as the crystal structure is broken.

19. How does the sun produce light?

The sun produces light through a process called nuclear fusion. In its core, hydrogen atoms fuse to form helium under extreme pressure and temperature, releasing enormous amounts of energy in the form of light and heat.

20. What are some examples of bioluminescent organisms?

Bioluminescent organisms produce their own light through chemical reactions. Examples include fireflies, some deep-sea fish, certain jellyfish species, and some fungi. This natural light production is often used for communication, attracting prey, or defense.

21. How does lightning generate light?

Lightning generates light when an electrical discharge occurs between oppositely charged regions in the atmosphere. This rapid release of electrical energy heats the air to extremely high temperatures, causing it to emit light in the form of a bright flash.

22. How does a candle produce light?

A candle produces light through a process called combustion. The heat from the flame melts and vaporizes the wax, which then reacts with oxygen in the air. This chemical reaction produces heat and light, with the flame's yellow color coming from glowing particles of carbon.

23. What is the principle behind plasma globes?

Plasma globes work on the principle of gas ionization. A high-voltage electrode at the center ionizes noble gases inside the globe. The resulting plasma filaments extend outward, creating colorful streaks of light. Touching the globe affects the electric field, causing the filaments to move towards your hand.

24. How do light sticks used in emergency situations work?

Emergency light sticks, similar to glow sticks, work through chemiluminescence. They contain two separate chemicals and a fluorescent dye. When the stick is bent, it breaks an inner container, allowing the chemicals to mix. This triggers a chemical reaction that excites the dye molecules, causing them to emit light. The light can last for several hours, making them useful in emergencies.

25. How do light-emitting animals use their bioluminescence?

Bioluminescent animals use their light-producing ability for various purposes:

26. How does the light from a flame change color based on temperature?

The color of a flame changes with temperature due to blackbody radiation. As the temperature increases, the flame color shifts from red to orange, then yellow, and finally to blue-white. This is why the hottest part of a flame (usually the base) appears blue, while the cooler parts are yellow or orange. The specific colors can also be influenced by the chemical composition of the burning material.

27. What is light pollution and how does it affect natural light sources?

Light pollution is excessive or misdirected artificial light that brightens the night sky. It affects natural light sources by:

28. How does the color rendering index (CRI) of a light source affect our perception of colors?

The Color Rendering Index (CRI) measures how accurately a light source reveals the colors of objects compared to natural light. A higher CRI (closer to 100) means colors appear more natural and vibrant. Low CRI lights can make colors look dull or distorted. This is important in settings where color accuracy is crucial, such as art galleries, retail stores, or in photography.

29. What is the difference between fluorescence and phosphorescence?

Both fluorescence and phosphorescence involve the absorption of energy and subsequent emission of light. The key difference is in the duration of light emission. Fluorescence stops almost immediately when the energy source is removed, while phosphorescence continues to emit light for a noticeable time after the energy source is gone.

30. How do glow sticks produce light?

Glow sticks produce light through a chemical reaction called chemiluminescence. When the stick is bent, it breaks an inner container, allowing two chemicals to mix. These chemicals react, producing energy that excites a fluorescent dye, which then emits light.

31. How do neon signs generate different colors?

Neon signs generate light through gas discharge. Different gases produce different colors when excited by an electric current. For example, neon gas produces red-orange light, while argon produces blue light. Other colors are created by using different gas mixtures or phosphor coatings inside the tubes.

32. How do lasers produce light?

Lasers produce light through a process called stimulated emission. Atoms in the laser medium are excited to higher energy states. When they return to lower energy states, they emit photons. These photons stimulate other excited atoms to emit identical photons, resulting in a coherent, intense beam of light.

33. What is the difference between thermal and non-thermal light sources?

Thermal light sources produce light as a result of their high temperature, like the sun or incandescent bulbs. Non-thermal light sources, such as LEDs or fluorescent lamps, produce light through other mechanisms like electronic transitions or chemical reactions, without relying on high temperatures.

34. How do fireflies produce light?

Fireflies produce light through a chemical reaction called bioluminescence. They have a light-producing organ where a chemical called luciferin reacts with oxygen, aided by an enzyme called luciferase. This reaction produces light with very little heat, making it a highly efficient light source.

35. How do different types of stars produce light?

Stars produce light primarily through nuclear fusion in their cores. The exact process depends on the star's mass and age. Main sequence stars like our sun fuse hydrogen into helium. Larger stars can fuse heavier elements, while white dwarfs emit light from residual heat.

36. What is electroluminescence and how is it used in lighting?

Electroluminescence is the production of light in response to an electric current or field. It's used in various lighting applications, including LED displays, backlights for LCD screens, and some types of night lights. The light is produced when electrons in a material are excited and then return to their ground state.

37. How do different types of light bulbs compare in terms of energy efficiency?

Energy efficiency in light bulbs is often measured by lumens per watt. LED bulbs are typically the most efficient, followed by CFL (Compact Fluorescent Lamps), then halogen incandescent, and finally traditional incandescent bulbs. LEDs can convert up to 90% of their energy to light, while incandescent bulbs convert only about 10% to light, with the rest becoming heat.

38. What is the difference between warm and cool light, and how is it produced?

Warm and cool light refer to the color temperature of the light, measured in Kelvin (K). Warm light (2700-3000K) has a yellowish hue, similar to traditional incandescent bulbs. Cool light (5000K and above) has a bluish tint, more like daylight. In artificial lights, this is achieved by using different phosphor coatings (in fluorescent and LED lights) or different filament temperatures (in incandescent bulbs).

39. What is the role of phosphors in artificial lighting?

Phosphors are substances that exhibit luminescence when exposed to radiation. In artificial lighting, they're crucial for creating white light in fluorescent lamps and many LED bulbs. In fluorescent lamps, phosphors coating the inside of the tube convert ultraviolet light into visible light. In white LEDs, blue light from the LED chip excites a yellow phosphor, which combines with some of the blue light to produce white light.

40. How does the light from a computer or phone screen differ from natural light?

Computer and phone screens typically emit blue-rich light, which is different from the balanced spectrum of natural daylight. This artificial light is produced by LEDs or LCD technology. The higher proportion of blue light can affect our circadian rhythms, potentially disrupting sleep patterns if used extensively before bedtime. Natural light, on the other hand, changes in color temperature throughout the day, helping to regulate our biological clock.

41. What is the difference between photoluminescence and chemiluminescence?

Photoluminescence and chemiluminescence are two different mechanisms of light production:

42. What is the principle behind fiber optic lighting?

Fiber optic lighting works on the principle of total internal reflection. Light enters one end of a thin, flexible fiber and is reflected off the inner walls as it travels along the fiber's length. This allows light to be transmitted over long distances with minimal loss, even around bends. In lighting applications, a single light source can illuminate multiple fiber optic strands, creating unique lighting effects.

43. How do different atmospheric conditions affect the appearance of natural light?

Atmospheric conditions can significantly alter the appearance of natural light:

44. How do different types of artificial lights affect plant growth?

Different artificial lights affect plant growth in various ways:

45. What is the difference between luminous flux, luminous intensity, and illuminance?

These are different measures of light:

46. What is the role of quantum mechanics in light production?

Quantum mechanics is fundamental to understanding light production at the atomic level. It explains:

47. How do different light sources affect human circadian rhythms?

Light sources can significantly impact human circadian rhythms:

48. What is the principle behind holographic displays, and how do they create 3D images?

Holographic displays create 3D images by using the principles of light interference and diffraction. They work by:

49. How do light-sensitive pigments in the human eye detect different colors?

The human eye detects colors using specialized cells called cones in the retina. There are three types of cones, each sensitive to different wavelengths of light: