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# 9 Difference Between Conduction, Convection and Radiation

written by Stanley Udegbunam || Dec 19, 2020

## OVERVIEW OF CONDUCTION, CONVECTION AND RADIATION

Matter exists in different forms, it could be solid, liquid or gas.

If two objects with different temperatures are brought in contact, heat transfer will take place.

The heat will flow from the object with a higher temperature to the one with a lower temperature.

The energy transferred is called thermal energy.

There are three modes of heat transfer: conduction, convection and radiation.

Let us use a table to properly differentiate between these heat transfer modes.

## 9 DIFFERENCE BETWEEN CONDUCTION, CONVECTION AND RADIATION

1.Conduction is the transfer of heat through the molecular collision of matter.Convection is a process of heat transfer that involves the physical transport of bulk matter.Radiation is the transport of thermally generated electromagnetic waves
2.Requires the existence of a material medium before heat can be transferred.Requires the existence of a material medium for its propagation.Does not require the existence of an intervening material medium for its propagation.
3.Occurs in solidOccurs in fluids (liquids and gases).Heat is radiated mostly from radioactive substance.
4.Heat is conducted by direct contact with the heat source.Convective current is set up and heat is transferred through the fluids exchanging heat.Heat travels through vacuum.
5.Involves micro-movement (movement of micro particles)Involves Macro/bulk movementMovement of electromagnetic waves.
6.Heat transfer is agitated by temperature difference.Heat transfer is agitated by density difference.Heat transfer occurs in all object with a temperature greater than 0 K.
7.It is not guided by the law of reflection and refraction.It does not follow the laws of reflection and refraction.It follows the law of reflection and refraction because radiation can occur through a medium that is transparent or translucent to the radiation.
8.Conduction is calculated using Fourier’s Law of conduction.Convection is calculated using Newton Laws of Cooling.Radiation is calculated using Stefan-Boltzmann law.
9.There are three types of conduction:
• Thermal Conduction
• Electrical Conduction
• Sound Conduction
There are two types of convection:
• Forced Convection
• Natural Convection
Radiation can only be one of two types:

swipe sideways to see complete table

1.Conduction is the transfer of heat through the molecular collision of matter.Convection is a process of heat transfer that involves the physical transport of bulk matter.Radiation is the transport of thermally generated electromagnetic waves
2.Requires the existence of a material medium before heat can be transferred.Requires the existence of a material medium for its propagation.Does not require the existence of an intervening material medium for its propagation.
3.Occurs in solidOccurs in fluids (liquids and gases).Heat is radiated mostly from radioactive substance.
4.Heat is conducted by direct contact with the heat source.Convective current is set up and heat is transferred through the fluids exchanging heat.Heat travels through vacuum.
5.Involves micro-movement (movement of micro particles)Involves Macro/bulk movementMovement of electromagnetic waves.
6.Heat transfer is agitated by temperature difference.Heat transfer is agitated by density difference.Heat transfer occurs in all object with a temperature greater than 0 K.
7.It is not guided by the law of reflection and refraction.It does not follow the laws of reflection and refraction.It follows the law of reflection and refraction because radiation can occur through a medium that is transparent or translucent to the radiation.
8.Conduction is calculated using Fourier’s Law of conduction.Convection is calculated using Newton Laws of Cooling.Radiation is calculated using Stefan-Boltzmann law.
9.There are three types of conduction:
• Thermal Conduction
• Electrical Conduction
• Sound Conduction
There are two types of convection:
• Forced Convection
• Natural Convection
Radiation can only be one of two types:

## FURTHER EXPLANATION

We’ve clearly stated the differences between the three modes of heat transfer.

But it’s also important to note that heat can be transferred through more than one heating process simultaneously.

different modes of heat transfer

For instance:

If a pot of boiling water is placed on the boiler, the heat is first transferred to the bottom of the pot through conduction.

This heat makes the layer of water at the bottom to be less dense.

The less dense layers will move to the top and the upper layers of the water which is now more dense will fall to the bottom where they get heated too.

This heating process builds up convective current and the entire water is heated up through convection.

Standing a little distance from the boiling water we can feel the heat on the surface of our skin due to radiation.

# 9 Major Differences

written by Stanley Udegbunam || Dec 18, 2020

## OVERVIEW OF HEAT VS TEMPERATURE

We can’t talk about heat without mentioning temperature.

Heat and temperature are two closely related terms but a clear distinction exists between the two of them.

The first major difference lies in their definition.

Heat is a form of energy that is transferred from one body to another as a result of the difference in temperature while temperature is the measure of the degree of hotness or coldness of a body.

Let us take a look into other key differences.

## DIFFERENCE BETWEEN HEAT AND TEMPERATURE

HEAT

TEMPERATURE
1.Heat is a form of energy that is transferred from one body to another as a result of difference in temperature.Temperature is the measure of the degree of hotness or coldness of a body.
2.The total energy (kinetic energy and potential energy) obtained by molecules in an object.The average kinetic energy of molecules in an object.
3.an extensive propertyAn intensive property
4.Flows from hot body to cold body.Rises when the object is heated and falls when cooled down.
5.Measured by the calorimeter.Measured by the thermometer.
6.Has a working ability.Does not have working ability.
7.S.I unit is Joules (J)It’s S.I unit is Kelvin (K), Celsius (C) or Fahrenheit (F)
8.Represented by “Q”.Represented by “T”.
9.It is a vector quantityIt is a scaler quantity

HEAT

TEMPERATURE
1.Heat is a form of energy that is transferred from one body to another as a result of difference in temperature.Temperature is the measure of the degree of hotness or coldness of a body.
2.The total energy (kinetic energy and potential energy) obtained by molecules in an object.The average kinetic energy of molecules in an object.
3.an extensive propertyAn intensive property
4.Flows from hot body to cold body.Rises when the object is heated and falls when cooled down.
5.Measured by the calorimeter.Measured by the thermometer.
6.Has a working ability.Does not have working ability.
7.S.I unit is Joules (J)S.I unit is Kelvin (K), Celsius (C) or Fahrenheit (F)
8.Represented by “Q”.Represented by “T”.
9.It is a vector quantityA scaler quantity

If two objects with different temperatures are brought in contact, they will be heat transfer between them.

This could go on until thermal equilibrium is reached.

Heat energy is also known as thermal energy.

If the thermal energy is increased, the temperature of the object will rise and thermal equilibrium will be reached in a shorter time.

From this, we can deduce that thermal energy is directly proportional to temperature.

Calorimeter – Heat Measuring Device

Thermometer – Temperature Measuring Device

# 13 Differences and Similarities

written by Stanley Udegbunam || Dec 17, 2020

## OVERVIEW OF EVAPORATION AND BOILING

Evaporation and boiling are two types of vaporization.

Since the beginning of man, there is always this subtle confusion between boiling and evaporation.

These days, they are used interchangeably which isn’t right.

In as much as they are both types of vaporization, a clear difference still exists between both terms.

Evaporation is a natural silent process that occurs when a liquid is exposed to an unsaturated gaseous medium while boiling is a liquid to the gaseous phase transition that is induced by external heat.

Let’s take a look at the major differences between these vaporization types in a tabular view.

## DIFFERENCE BETWEEN EVAPORATION AND BOILING

EVAPORATION

BOILING
1.It’s the phase change from liquid to gas
below the boiling temperature at a given pressure.
It’s the phase change from liquid to gas at the boiling point of the liquid.
2.Evaporation occurs only at the surface of the liquid.It is a bulk phenomenon. It occurs throughout the volume of the liquid.
3.It is a natural process. It is often induced.
4.Occurs at all temperature.Occurs at a definite temperature (boiling temperature) at particular pressure.
5.The energy required is often supplied by the surrounding atmosphere and its own internal energy.External source of energy is needed for boiling to occur.
6.Bubbles do not form in evaporation.Bubble formation is visible.
7.Evaporation takes place silently.Because of the continuous bubble formation and collapse, boiling is a noisy process.
8.As evaporation occurs, the temperature of the liquid decreases gradually.During boiling, the temperature of the liquid remains constant.
9.Evaporation is a very slow vaporization
process.
Boiling is a rapid process.

EVAPORATION

BOILING
1.It’s the phase change from liquid to gas
below the boiling temperature at a given pressure.
It’s the phase change from liquid to gas at the boiling point of the liquid.
2.Evaporation occurs only at the surface of the liquid.It is a bulk phenomenon. It occurs throughout the volume of the liquid.
3.It is a natural process. It is often induced.
4.Occurs at all temperature.Occurs at a definite temperature (boiling temperature) at particular pressure.
5.The energy required is often supplied by the surrounding atmosphere and its own internal energy.External source of energy is needed for boiling to occur.
6.Bubbles do not form in evaporation.Bubble formation is visible.
7.Evaporation takes place silently.Because of the continuous bubble formation and collapse, boiling is a noisy process.
8.As evaporation occurs, the temperature of the liquid decreases gradually.During boiling, the temperature of the liquid remains constant.
9.Evaporation is a very slow vaporization
process.
Boiling is a rapid process.

## SIMILARITIES BETWEEN EVAPORATION AND BOILING

Despite the numerous differences, we can still point out a few similarities.

The similarities between evaporation and boiling include:

1. Both cause phase transition from liquid to vapor.
2. They don’t alter the chemical composition of the liquid so they are both physical changes.
3. Both require energy. Usually thermal energy, but other forms of energy can also be used in order to increase the kinetic energy of the molecules, thus making them evaporate or boil.
4. Lastly, both depend on one or more external conditions like surrounding air pressure, humidity and temperature of air or temperature of the liquid.

evaporation – a surface phenomenom

boiling – throughout the liquid volume (at b.point)

## SUMMARY (EVAPORATION VS BOILING)

There is obviously a clear difference between evaporation and boiling.

Even if you forget the majority of the differences, never forget that:

Evaporation occurs only at the surface of the liquid while boiling occurs throughout the volume of the liquid.

# Any Cause For Alarm? 💊

written by Stanley Udegbunam || Dec 16, 2020

The human body is like a living furnace constantly producing its own heat.

There is a certain body temperature required for proper body function and metabolism.

Your body temperature might be slightly higher or lower than the stated average body temperature.

But if there is a significant deviation, then it signifies a health problem.

Let’s dive a little bit into details.

## WHAT IS THE NORMAL BODY TEMPERATURE?

The average normal body temperature is  37°C (98.6°F).

Since it’s an average value, it may vary based on age, activity, time of day and also the body part of the reading was taken.

Therefore we often talk about the average body temperature range which falls within  36.1°C (97°F) —- 37.2°C (99°F) for adults.

## WHAT IS THE AVERAGE BODY TEMPERATURE RANGE?

The average body temperature range is estimated as:

 ADULTS ranges from 36.1°C (97°F) —- 37.2°C (99°F) BABIES & CHILDREN Ranges from 36.6°C (97.9°F) — 37.2°C (99°F) ADULTS OVER 65 lower than 36.2°C (98.6°F)

## FACTORS AFFECTING NORMAL BODY TEMPERATURE

Normal body temperature may slightly vary above or below the average body temperature as a result of different factors like:

• A person’s age. Younger people tend to have higher average body temperatures.
• Physical activity levels
• The time of the day. Body temperature is lowest in the morning and highest in the late afternoon.
• Food and fluid intake
• For females, their hormones and their menstrual cycle affect their body temperature.
• The body part the reading is taken affects the temperature value.

Rectal readings (ear) are higher than oral readings (mouth), while armpit readings tend to be the lowest.

From left to right, increasing order of temperature value.

## WHAT DOES A BODY TEMPERATURE ABOVE 37°C MEAN?

If the temperature is appreciable higher than the normal body temperature of 37°C, then it is a sign of fever.

The following thermometer readings are generally a sign of a fever:

• Rectal or ear readings: 38°C (100.4°F) or higher
• Mouth reading: 37.8°C (100°F) or higher
• Armpit readings 37.2°C (99°F) or higher

Fever can be accompanied by other signs and symptoms like:

• Sweating
• Loss of appetite
• Hot skin
• Increased heart rate
• Dehydration
• Body aches
• Fatigue and weakness
• Chills or shivering

You can suffer from fever whenever you overwork yourself or trying to adjust to a new environment.

Most times, all you need is to have a good rest but if symptoms persist, see a doctor.

## WHAT DOES A BODY TEMPERATURE BELOW 37°C MEAN?

If the body temperature is lower than the normal average body temperature of 37°C, it is a sign of hypothermia.

Hypothermia is a condition when the body’s core temperature is significantly below the normal temperature required for proper body function and metabolism.

Hypothermia is not a disease. It occurs when you lose too much body heat.

For Babies: Below 36.1°C (97°F)

Other signs and symptoms of hypothermia include:

• A weak pulse
• Slow, shallow breath
• Low energy or dizziness
• Loss of consciousness
• Bright red skin that’s cold to the touch (in babies)
• Shivering
• Poor coordination or clumsiness
• Confusion or memory loss

Most people associate hypothermia with being outside in cold weather for long periods of time. But hypothermia can occur indoors, too.

Babies and older adults are more susceptible.

Babies are not good at regulating their temperature and as a result, they can lose heat quickly.

It’s therefore important to always keep them warm.

Older adults also struggle to keep their body temperature within the normal range if they are in a room with intense air conditioning.

Exercise helps regulate body temperature.

If you are not feeling too well, it’s advised to check your body temperature.

Proceed to see a medical practitioner if you notice deviations or for clarity.

# 20 Common Examples of Radiation

Written by Stanley Udegbunam || Dec 10, 2020

### Table of Content

#### AFRILCATE

Radiation is one of the fundamental modes of heat transfer others been conduction and convection.

Radiation is the transport of thermally generated electromagnetic waves.

It does not require the existence of an intervening material medium for heat to be transferred from one surface to the other.

Rather, it can be transferred through a vacuum or through a medium that is transparent or translucent to the radiation.

Radioactive atoms are atoms with unstable nuclei.

To attain stability, these atoms emit the excess energy by radioactive decay.

Let us take a glance at the various common examples of radiation.

Listed below are 20 common examples of radiation in everyday life.

1. Light rays from the sun
2. Remote controls
3. Visible light from a bulb/lantern
7. Heat from a stove burner or camp fire
8. X-rays
9. Laser beam
11. Airport security scanners
12. Microwave ovens
13. CT scans
14. Black lights
15. WIFI-Router
16. Bluetooth speakers
18. Aircraft communication
19. Neon lamps
20. Power Lines

Radiation cannot be detected by human senses.

A variety of handheld and laboratory instruments is available for detecting and measuring radiation.

The most common handheld or portable instruments are:

• Geiger Counter
• MicroR Meter, with Sodium Iodide Detector
• Portable Multichannel Analyzer
• Ionization (Ion) chamber
• Neutron REM Meter, with Proportional Counter

# 10 Common Examples of Convection (with pictures)

Written by Stanley Udegbunam || Dec 10, 2020

In today’s article, we will be looking at 10 different examples of convection with pictures and detailed explanations.

We will start by having a quick overview just to remind ourselves of what convections actually means, then proceed afterwards.

# OVERVIEW OF CONVECTION

Convection is a process of heat transfer that involves the physical transport of bulk matter from one point to another.

It is one of the three modes of heat transfer, the others been conduction and radiation.

There are two types of convection: Natural convection and Forced convection.

Unlike conduction, convection requires macroscopic movement of matter.

As a result of this, convective heat transfer only occurs through liquid and gases.

Heat transfer is only possible when temperature difference between the two fluids exchanging heat.

When a surface is exposed to ambient air at different temperature, convection heat transfer takes place between the surface and the ambient air.

The heat flow rate from surface to ambient air is governed by Newton’s Law of Cooling.

## 10 EXAMPLES OF CONVECTION

Listed below are 10 common examples of convection in everyday life.

1. Boiling Water
2. Land and Sea Breeze
3. Air Conditioner
4. Body blood circulation
5. Melting of chilled drinks
6. Convection Oven
7. Hot-air Baloon
8. Refrigerator
10. Defrosting frozen meat

## DETAILED EXPLANATION OF THE CONVECTION EXAMPLES

### 1. Boiling Water

This is the most common and relatable household example of convection.

For instance,

When water is heated in a kettle, thermal expansion takes place.

The lower layer of the water which is hotter becomes less dense and moves upward due to buoyancy.

The cooler/upper layer of the water falls below and gets heated as well.

The process is repeated until the entire water in the kettle is heated up.

### 2. Land and Sea Breeze

This type of convection occurs naturally, it’s either called natural convection or free convection.

In the daytime, the land surface is heated up making it warmer than a nearby sea.

The heated air molecule moves up and it’s replaced by cooler air from the sea resulting in what we call “Sea Breeze.”

This repetitive circular motion creates a convective current.

At night, the reverse is the case. The air above the sea is warmer compared to that of the land.

As a result of convection, the warm air from the sea rises and is replaced by the cooler air from the land resulting in what we term also as “Land Breeze.”

Now the question is…

#### Why is land and sea breeze called natural convection?

Land and sea breeze is called natural convection because convective current moves air molecules across the land and sea intermittently depending on their respective temperature difference.

This convective process is a natural process completely devoid of any form of human intervention.

### 3. Air Conditioner

Most of you can’t do without the air-conditioners or high blowing electric fans during the hot summer season. (actually referring to myself😉).

Air conditioner cools the room or containing structure through the same principle of convection.

When turned on, it releases cool air.

This released air falls below the warm air and quickly fills up the room because it’s denser.

The warm air, which is less dense rises above the cool air and it’s sucked into the compressor of the air-conditioner.

The continuous sucking out of warm air while filling the room with cooler air sets up a convection current.

The human body continually produces warm air as well as on-going activities in the room.

As long as the air conditioner is turned on, this warm air will always be replaced by cool air.

### 4. Body Blood Circulation

You are probably wondering what’s the relationship between convection  and blood circulation, right?…

Yeah, convection do occur in the human heart in order to regulate body temperature.

Although the heart is a single organ, it acts as a double pump.

The first pump carries oxygen-poor blood to your lungs, where it unloads carbon dioxide and picks up oxygen. It then delivers oxygen-rich blood back to your heart.

The second pump delivers the oxygen-rich blood to every part of your body.

Inother words, the heart serves as a pump that delivers blood to different parts of the human body through forced convection.

Forced convection is a type of convection that involves fluid flow under the action of driving forces like pressure.

In forced convection, the fluid is “forced” to flow over a surface or in a tube by external means such as pumps or fans.

The heart is the best example of forced convection in our body.

### 5. Melting of Chilled Drink

If you take an ice-cold drink like this gorgeous beer here, away from the chiller and expose it to the ambient air, it will defrost with time.

This is because the temperature of the bottle surface increases as warm air blows over it.

Since a convection current is set, the temperature of the bottle surface is gradually altered and the chilled drink melts.

After a long time, it will be at the same temperature with the environment.

### 6. Convection Oven

Convection oven is quite different from the regular oven.

The regular oven (common in houses) conducts heat through conduction directly from the oven heater to the oven rack.

But in a convection oven, the heat is evenly dispersed by fans inside the oven.

The heated air in the oven expands and rises and the cool air falls low and it’s heated as well.

For baking purposes, the convection oven is preferred to the regular oven type because:

the convective process set up in the oven thoroughly cooks the food accross all sides giving you an evenly cooked cake or mouth-watering steak.

### 7. Hot Air Baloon

Hot air balloons use the same principle of convection.

A heat source at the bottom of the balloon heats the air molecules around the flame, causing them to move upwards.

The hot air which moves upward gets trapped inside the balloon, causing the balloon to rise up too.

The cool air is pushed downward, where it is also heated and it rises too to further push the balloon upward.

Through this convection process, the balloon keeps moving in the upward direction.

To land the hot air balloon, a large mass of hot air is released.

By so doing, cool air replaces the hot air and the balloon lowers gradually until it reaches ground level.

hot-air ballooning

### 8. Refrigerator

Another common example of convection heat transfer is the household refrigerator.

The process by which a refrigerator removes heat from the refrigeration compartments relies on the concept of convection.

In refrigerators, convection occurs through the use of refrigerant gases and compressor.

The convection oven mentioned above uses circulating air to help speed up the process of cooking food.

Refrigerators use copper tubes filled with refrigerant coolants to produce the cooling effect required for food preservation.

A motor radiator is a mechanical device that cools the hot liquid circulating through the block of an internal combustion engine.

In automobile, this liquid is called coolant.

Hot coolant finds its way to the radiator through radiator tubes. Cool air from the environment also passes through the fins of the radiator as you drive.

The cool air passing through the radiator fins helps cools the hot coolant.

The temperature of the coolant drops gradually after which it runs through the engine again to pick up more heat and travels back to the radiator.

The heat is transferred from the hot coolant to the cool air through convection and the process continues.

It’s important to note that the nearby heated air is transmitted to the environment through radiation.

So, we can identify two modes of heat transfer around a radiator, convection and radiation.

Convection transfers the heat from the coolant to the surrounding air through the radiator fins,

while radiation transmits the heated surrounding air to the environment.

This brings us to another important question.

Since this mechanical device involves two modes of heat transfer (convection and radiation), why are they called car radiators instead of car convectors?

Well, it is called radiators instead of convectors, because of the fins surrounding the mechanical device.

Mechanical fins are extended surfaces that enhance radiation heat transfer, simply by increasing the surface area of the device.

Heat lost through car radiators is a forced type of convection.

### 10. Defrosting Frozen meat

What is the most annoying challenge you’ve encountered while cooking?

For me, I’ll say it’s forgetting to take off frozen meat or fish from the freezer few hours before cooking.

The process of defrosting frozen food is called thawing.

We can achieve thawing in two ways:

• leaving it in open-air – this can take up to 10 – 15 hours depending on how frozen the meat is.
• Placing it under a running tap – this is quicker and defrosts the meat in 11-20 minutes.

Both options utilize the principle of convection to achieve thawing.

For the case of running tap, thawing is faster because the continuous downpour of water will lead to a faster heat transfer.

If the water is warm or hot, then the time spent in defrosting will reduce.

Inorder words, the higher the water temperature, the more heat is transferred through convection and the faster the thawing.