Candle Flame - Types, Structure, Different Zones, Candles with FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:52 PM IST

In this article we will be discussing candle flame, what is flame, different zones of candle flame, types of candles, zones of candle flame, structure of flame, types of flame, hottest part of flame, flame temperature, oxidizing flame, flame diagram, burning flame, middle zone of candle flame, luminous part of candle flame, burning candle experiment observations, yellow flame, non luminous zone, hottest region of Bunsen flame, blue flame meaning, layers of flame, flame color temperature chart, hottest flame color, outermost zone of candle flame, and partial combustion.

This Story also Contains

What is Flame?
Types of Flames
Structure of Flame
Different Zones of Candle Flame
Flame Color Temperature Chart
Types of candles

What is Flame?

Flame definition: When a mixture of air and combustible gas rapidly reacts, it displays self-propagating heat and light. This is caused due to the exothermic chemical reaction of gases which vaporize on burning. The unburned mixture starts reacting exothermic manner until the temperature reaches ignition temperature (ignition temperature is the temperature at which any combustible substance starts undergoing combustion and catches fire) and mixture starts burning. This is when we can see hot luminous flames emerging from a substance.

Also read -

Types of Flames

Flames can be categorized on the basis of composition, structure of flame and other characteristics. When fuel gas and air is mixed prior to entering the burner premixed gas flames arise. Diffusion flames are flames which arise when fuel gas and air are mixed after leaving the burner. When the rate of gas flow is relatively low, the incoming gaseous flow of fuel and air is in constant streamline and without turbulence. Such flames are called laminar flames. Flames can also be categorized into stationary flames which are most widely used in domestic or industrial burners and propagating (travelling) flames which are involved in explosions. The Bunsen burner flame is a flat flame used from a special burner which produces uniform flow.

NEET Highest Scoring Chapters & Topics

This ebook serves as a valuable study guide for NEET exams, specifically designed to assist students in light of recent changes and the removal of certain topics from the NEET exam.

Download EBook

Flames can also be categorized as three basic welding flames namely:

Natural flame: natural flame two zones the inner zone with white color and the outer zone with blue color. Inner zone has a temperature of 3100°C and the outer zone has a temperature of nearly 1275°C. This flame has equal amounts of oxygen and fuel gas which burns completely without affecting the metal that needs wielding.

Carburizing flame: Carburizing flame is used to weld carbon, steel, nickel and it has three zones, namely, the inner zone, the intermediate zone and the outer cone. The inner zone is of white color with a 2900°C temperature, the intermediate zone reflects red color and the outer cone is of blue color.

Oxidizing flame: Oxidizing flame is obtained when in a fuel mixture of natural flame, acetylene reduces or amount of oxygen increases, the inner cone disappears. This type of flame is hotter than natural flame and has two well-defined zones. The inner zone is of very bright white color while the outer flame is of blue color. The temperature of the inner zone is nearly 3300°C.

Flames can also be categorized on the basis of luminescence:

Non luminous flame: When fuel is burnt in presence of abundant oxygen it produces non luminous flame which is also called blue flame. It is an oxidizing flame. This is hotter and brighter than non luminous flame and used in stoves.

When fuel is burnt in presence of abundant oxygen it produces non luminous flame which is also called blue flame. It is an oxidizing flame. This is hotter and brighter than non luminous flame and used in stoves.

Luminous flame: When fuel is burnt in presence of limited oxygen it produces non luminous flame which is also called yellow flame. It is a reducing flame. This is also hot and bright but less than non luminous flame. Example: candle flame.

When fuel is burnt in presence of limited oxygen it produces non luminous flame which is also called yellow flame. It is a reducing flame. This is also hot and bright but less than non luminous flame.

Image depicting burning flame

Structure of Flame

Image depicting structure of candle flame

Different Zones of Candle Flame

Zones of candle flame can be categorized on the basis of color, luminescence and temperature.

Outermost zone: This zone forms the veil of a candle flame. It is a non luminous part of flame. It is slightly bluish in color and is the hottest part of flame with flame temperature 1400°C approx. It is made up of completely burnt wax.
Middle zone: The middle zone of a candle flame is the bright luminous zone of candle flame which is made up of partially burnt wax. This zone is yellow in color and is moderately hot with flame temperature 1200°C approx. In this zone carbon undergoes partial combustion which leads to the formation of ashes and soot.
Innermost zone: This is the least hot part of a flame. This zone is made up of two zones named as:
Dark zone: There is no burning of fuel in this zone. This zone consists of unburnt wax vapors. It is cooler than the middle and outermost zone with flame temperature 1000°C approx.
Blue zone: in this zone, carbon monoxide bums completely with a blue flame as the vaporized wax gets oxidized to form carbon monoxide. It is near the base of the flame and the coolest part of the flame with flame temperature 800°C.

Also read : NCERT Solutions for Class 8 Science Chapter 6 - Combustion and Flame

Flame Color Temperature Chart

However, It is not convenient practice to differentiate zones of candle flame according to color because different flames burn with different color according to the oxygen supplied. The following flame diagram depicts how the color of a flame changes with respect to oxygen supply.

From 1 to 4, oxygen supply is increased and thus the color of parts of a flame is changing.

NCERT Chemistry Notes:

Types of candles

On the basis of material use candles can be categorized as:

Paraffin Wax Candles
Soy Wax Candles
Palm Wax Candles
Beeswax Candles
Bayberry Wax Candles
Liquid Wax Candles

Also check-

Frequently Asked Questions (FAQs)

1. Define flames.

When a mixture of air and combustible gas rapidly reacts, it displays self-propagating heat and light called flame.

2. Explain blue flame meaning.

When fuel is burnt in presence of abundant oxygen it produces a non luminous flame which is also called blue flame. It is an oxidizing flame. This is hotter and brighter than non luminous flame and used in stoves.

3. Which zone of candle flame is the hottest?

The hottest zone of flame is the outermost zone.

4. Candle is made up of which material?

Candle is made up of following materials:

Paraffin Wax Candles
Soy Wax Candles
Palm Wax Candles
Beeswax Candles
Bayberry Wax Candles
Liquid Wax Candles

Write burning candle experiment observations.

Ans. A candle is burnt in presence of oxygen, when the oxygen supply is limited the candle stops burning and goes off.

5. What is temperature of fire?

Temperature of fire depends on the composition of fuel. The temperature of flame can vary from 600°C to 300°C.

6. Which zone of the candle flame is luminous and why?

The middle zone of a candle flame is the bright luminous zone of candle flame which is made up of partially burnt wax. This zone is yellow in color and is moderately hot with flame temperature 1200°C approx. In this zone carbon undergoes partial combustion which leads to the formation of ashes and soot.

7. Why does a flame always points upwards?

Due to the burning of candles the nearby air gets heated up and starts to rise. This warm air descends upwards and cooler air and oxygen descends downward towards the bottom of the flame to replace it. When this cooler air is heated again, it is replaced by cooler air at the base of the flame as it rises upwards.

8. What is meant by luminous and non luminous flame?

Non luminous flame: When fuel is burnt in presence of abundant oxygen it produces non luminous blue flame. It is an oxidizing flame.

Luminous flame: When fuel is burnt in presence of limited oxygen it produces non luminous yellow flame. It is a reducing flame.

9. We can observe different colours while burning a candle. Why?

We can observe different colours while burning a candle because different regions of a candle flame combust with different rates, different temperatures and with different supply of oxygen.

10. Which gas burns with blue flame and what is blue flame temperature?

Methane (1960°C), carbon monoxide (2,121 °C), propane all burn with blue flame (1980°C).

11. What are the main zones of a candle flame?

The main zones of a candle flame are: 1) The blue base (hottest), 2) The dark inner core (vaporized, unburned fuel), 3) The yellow-orange luminous zone (where most light is emitted), and 4) The outer veil (faint blue, where complete combustion occurs).

12. Why is the center of a candle flame dark?

The center of a candle flame is dark because it contains vaporized wax that hasn't yet combusted. This area lacks oxygen and is cooler than the surrounding flame, so it doesn't emit light.

13. What causes the flickering of a candle flame?

Candle flames flicker due to air currents and variations in fuel supply. As the heated air rises, it creates convection currents that cause the flame to move. Inconsistencies in wax vaporization can also contribute to flickering.

14. Why does a candle flame always point upward?

A candle flame points upward due to convection. As the hot gases in the flame rise (because they're less dense than the surrounding air), they create an upward flow that shapes the flame vertically.

15. How does the wick of a candle work?

The wick of a candle works through capillary action. It draws liquid wax upwards, where the heat of the flame vaporizes it. The wick also provides a surface for the vaporized fuel to burn, maintaining the flame.

16. Why does a candle flame have different colors?

A candle flame has different colors due to varying temperatures and chemical reactions within the flame. The blue base is hottest, the dark inner core contains unburned fuel, and the yellow-orange outer region is where most light is emitted.

17. What is the hottest part of a candle flame?

The hottest part of a candle flame is the pale blue region at the base of the flame. This area can reach temperatures of about 1400°C (2552°F), where complete combustion occurs due to sufficient oxygen supply.

18. Can a candle burn in zero gravity?

Yes, a candle can burn in zero gravity, but it looks very different. Without convection currents, the flame forms a sphere around the wick. It burns cooler and with a dimmer, bluer flame due to the lack of fresh oxygen supply.

19. What is the purpose of the blue base in a candle flame?

The blue base of a candle flame is where the most complete combustion occurs. It's the hottest part of the flame, where there's an optimal mix of fuel vapor and oxygen. This region ensures efficient burning of the fuel.

20. How does air movement affect a candle flame?

Air movement can significantly affect a candle flame. Gentle air currents can cause the flame to flicker or lean. Stronger air movements can make the flame burn unevenly, produce more soot, or even extinguish it by disrupting the fuel-oxygen balance.

21. What chemical reaction occurs in a candle flame?

The main chemical reaction in a candle flame is combustion. The hydrocarbon molecules in the wax (typically paraffin) react with oxygen in the air to produce carbon dioxide and water vapor, along with heat and light.

22. What is the fuel in a candle flame?

The primary fuel in a candle flame is vaporized wax. As the solid wax melts and is drawn up the wick, it vaporizes due to the heat of the flame. This vaporized wax then mixes with oxygen in the air and combusts.

23. What role does oxygen play in a candle flame?

Oxygen is crucial for the combustion process in a candle flame. It combines with the vaporized wax fuel to produce the chemical reaction that generates heat and light. Without sufficient oxygen, the flame will dim and eventually extinguish.

24. Why does blowing gently on a candle make the flame brighter?

Blowing gently on a candle increases the oxygen supply to the flame. This extra oxygen allows for more complete combustion of the fuel, resulting in a brighter, hotter flame. However, blowing too hard will extinguish the flame by disrupting the fuel supply.

25. What happens if you put a glass over a burning candle?

If you put a glass over a burning candle, the flame will eventually go out. This happens because the flame consumes the available oxygen inside the glass. Once the oxygen is depleted, combustion can't continue, and the flame extinguishes.

26. What is the difference between a diffusion flame and a premixed flame?

A candle flame is a diffusion flame, where the fuel (vaporized wax) and oxidizer (air) mix through diffusion at the flame boundary. In contrast, a premixed flame, like in a gas stove, has the fuel and oxidizer mixed before combustion, resulting in a more efficient and hotter flame.

27. How does altitude affect candle burning?

At higher altitudes, where the air pressure and oxygen concentration are lower, candles may burn with a smaller, dimmer flame. The reduced oxygen can lead to incomplete combustion, potentially causing more sooting and a shorter burn time.

28. Why does a candle flame appear yellow?

The yellow color in a candle flame comes from incandescent carbon particles. These particles are produced when there's incomplete combustion in the fuel-rich regions of the flame. They get heated to the point of glowing, giving the flame its characteristic yellow color.

29. How does the length of the wick affect the candle flame?

The length of the wick affects how much fuel is drawn up and how high the flame burns. A longer wick will draw up more fuel, resulting in a larger, potentially smokier flame. A shorter wick produces a smaller, more controlled flame.

30. How does the composition of the wax affect the candle flame?

The composition of the wax affects the candle flame in several ways. Different waxes have different melting points and combustion characteristics. For example, beeswax burns hotter and cleaner than paraffin wax, while soy wax tends to burn cooler and longer.

31. Why do some candles produce more soot than others?

Candles produce soot when there's incomplete combustion of the fuel. This can happen due to factors like poor-quality wax, an incorrectly sized wick, or insufficient oxygen supply. Paraffin candles typically produce more soot than soy or beeswax candles.

32. How does the shape of a candle affect its burning?

The shape of a candle affects how it burns by influencing the way the wax melts and pools. Tapered candles tend to burn more evenly as the melted wax runs down the sides. Wider candles may form a deeper pool of melted wax, which can affect the flame's stability.

33. Why do some candles tunnel?

Candle tunneling occurs when only the center of the candle burns, leaving a ring of unmelted wax around the edges. This usually happens when the candle isn't burned long enough for the entire top layer to melt, or if the wick is too small for the candle's diameter.

34. How does the size of the wick affect the candle flame?

The size of the wick affects how much fuel (melted wax) is drawn up and vaporized. A larger wick will draw up more fuel, resulting in a larger flame. However, if the wick is too large for the candle, it can lead to excessive fuel consumption and sooting.

35. What causes a candle to smoke?

A candle smokes when there's incomplete combustion of the fuel. This can happen if the wick is too long, causing more fuel to be drawn up than can be fully burned, or if there's insufficient oxygen supply to the flame.

36. What is a candle flame?

A candle flame is the visible, light-emitting part of a burning candle. It's a complex chemical reaction where the wax fuel is vaporized, mixed with oxygen, and ignited, producing heat and light.

37. What happens to the wax as a candle burns?

As a candle burns, the solid wax near the wick melts into a liquid. This liquid is then drawn up the wick through capillary action, where it vaporizes due to the heat of the flame. The vaporized wax then combusts, producing the visible flame.

38. What is the role of convection in a candle flame?

Convection plays a crucial role in shaping and maintaining a candle flame. As hot gases rise due to their lower density, they create an upward flow that gives the flame its typical tear-drop shape. This convection also brings fresh oxygen to the flame and removes combustion products.

39. What causes a candle to self-extinguish?

A candle can self-extinguish if the wick becomes too short to reach the fuel, if there's insufficient oxygen supply, or if the heat from the flame is insufficient to continue melting the wax. Some candles are designed to self-extinguish as a safety feature.

40. How does the shape of the candle container affect the flame?

The shape of the candle container can affect air flow around the flame and heat distribution. A narrow container might restrict oxygen supply, leading to incomplete combustion. A wide container might allow too much heat dissipation, affecting the size of the melt pool.

41. How does the color of a candle affect its flame?

The color of the candle wax doesn't significantly affect the color of the flame. The flame color is primarily determined by the temperature of the combustion and the chemical composition of the fuel, not the color of the solid wax.

42. What causes a candle to burn unevenly?

Uneven burning in candles can be caused by several factors: drafts that push the flame to one side, an off-center or crooked wick, impurities in the wax, or uneven cooling that creates an uneven surface for subsequent burns.

43. How does the temperature of the room affect a candle's burning?

Room temperature can affect how a candle burns. In colder rooms, the wax may solidify more quickly, potentially leading to tunneling. In warmer rooms, the entire surface of the candle may melt more easily, promoting even burning.

44. What causes the crackling sound some candles make when burning?

The crackling sound in some candles is usually caused by impurities or moisture in the wax or wick. As these impurities heat up, they can create small pockets of steam or gas that pop, producing the crackling sound.

45. How does the diameter of a candle affect its burning rate?

The diameter of a candle affects its burning rate by influencing the size of the wax pool that forms. A wider candle will typically burn more slowly than a narrower one of the same height, as it takes longer for the flame to melt the entire surface of wax.

46. What is the purpose of adding fragrance oils to candles?

Fragrance oils are added to candles for aesthetic purposes, to release pleasant scents when the candle burns. These oils vaporize along with the wax, dispersing the fragrance into the air. However, they can sometimes affect the burning characteristics of the candle.

47. What is the role of the luminous zone in a candle flame?

The luminous zone is the bright, yellow-orange part of the flame where most of the light is emitted. In this zone, carbon particles produced by incomplete combustion are heated to incandescence, creating the flame's characteristic glow.

48. How does wind affect a candle flame?

Wind can significantly affect a candle flame. Gentle breezes can cause the flame to flicker or lean. Stronger winds can make the flame burn unevenly, produce more soot, or even extinguish it by disrupting the balance of fuel and oxygen or by cooling the flame below its ignition temperature.

49. What is the difference between a tea light and a regular candle in terms of flame characteristics?

Tea lights typically have a smaller, more consistent flame compared to regular candles. This is because they have a short wick and are contained in a small metal cup, which controls the amount of melted wax available as fuel. Regular candles can have more variable flames depending on their size and shape.

50. How does the presence of multiple wicks affect a candle's burning?

Multiple wicks in a candle can create a larger, more even melt pool and potentially a stronger scent throw. However, they also consume wax faster and generate more heat. The flames may interact, creating a more complex burning pattern and potentially a larger overall flame.

51. What is the effect of adding salt to a candle flame?

Adding salt to a candle flame can produce a yellow-orange color due to the sodium in the salt. This occurs because the heat of the flame excites the sodium atoms, causing them to emit light at their characteristic wavelength. It's a simple demonstration of flame test in chemistry.

52. How does the melting point of the wax affect the candle flame?

The melting point of the wax affects how quickly a pool of liquid wax forms around the wick. Waxes with lower melting points will form a larger melt pool more quickly, potentially leading to a larger flame. Higher melting point waxes may burn more slowly and steadily.

53. What causes the formation of "mushroom" wicks in candles?

"Mushroom" wicks form when carbon accumulates at the tip of the wick. This usually happens due to incomplete combustion, often caused by a wick that's too long or a lack of air flow. The carbon buildup can make the flame larger and smokier if not trimmed.

54. How does the color of light emitted by a candle flame change with temperature?

As the temperature of a candle flame increases, the color of light emitted shifts from red to orange to yellow to white-blue. This follows the principle of black-body radiation, where hotter objects emit shorter wavelengths of light.

55. What is the role of the outer veil in a candle flame?

The outer veil is the faint blue region at the very edge of the flame. This is where complete combustion occurs due to the abundance of oxygen. It's the boundary between the flame and the surrounding air, and it's often barely visible to the naked eye.

56. How does the presence of drafts affect candle burning?

Drafts can significantly affect candle burning. They can cause uneven burning by pushing the flame to one side, increase the rate of wax consumption, potentially lead to sooting, and in extreme cases, can extinguish the flame or create a fire hazard by causing the flame to flare up.

57. What is the effect of adding metal salts to a candle?

Adding metal salts to a candle can change the color of the flame. Different metals produce different colors when heated in a flame. For example, copper produces a green flame, while lithium produces a pink flame. This is the principle behind fireworks colors.

58. How does the purity of the wax affect the candle flame?

The purity of the wax can significantly affect the candle flame. Purer waxes tend to burn more cleanly with less soot. Impurities can cause uneven burning, increased sooting, and can affect the color and stability of the flame.

59. What causes the formation of a "memory ring" in candles?

A "memory ring" forms when a candle is not burned long enough for the entire top surface to melt. On subsequent burns, the candle tends to melt only to the edge of this previous melt pool, creating a ring of unmelted wax around the edge and potentially leading to tunneling.

60. How does the ambient temperature affect the burning of a candle?

Ambient temperature can affect candle burning in several ways. In colder environments, the wax may solidify more quickly, potentially leading to a smaller melt pool and tunneling. In warmer environments, the entire surface of the candle may melt more easily, promoting even burning but potentially shortening the candle's overall burn time.