Thermal energy transfer involves the transfer of internal energy, which is the total amount of kinetic energy and potential energy of all the particles in the system. There are three main methods of thermal energy transfer. These are convection, conduction, and radiation.
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Jetzt kostenlos anmeldenThermal energy transfer involves the transfer of internal energy, which is the total amount of kinetic energy and potential energy of all the particles in the system. There are three main methods of thermal energy transfer. These are convection, conduction, and radiation.
These are experiments used to investigate the behaviour of thermal energy transfer, depending on the method of energy transfer we are discussing.
Conduction is the transfer of thermal energy that is transmitted by collisions between atoms and molecules.
Convection is the transfer of thermal energy due to the movement of heated fluid.
There are two types of convection, namely, natural convection and forced convection. Natural convection occurs by the motion of fluid due to density differences in a fluid, which is caused by temperature differences. Forced convection occurs by a motion of fluid due to a pump or fan.
Radiation is the transfer of thermal energy in the form of electromagnetic radiation, which is emitted by a heated surface in all directions.
The aim of this experiment is to investigate the rate of conduction in different metals. More specifically, four different types of metal will be used to investigate which metal has the highest and lowest rate of conduction. Let us look at some examples below.
Some examples of conduction heat transfer are:
The most efficient method of heat transfer is conduction. This method of heat transfer occurs when there is a temperature gradient across a body.
Firstly we attach ball bearings onto a stand and position a Bunsen-type burner underneath the ball bearings.
Then we position four different types of metal strips of equal width and length on the ball bearings, two horizontally and two vertically such that they meet at the centre, as seen in figure 1. These four metals are iron, brass, copper, and aluminium.
Using wax, we attach the metal strips to the ball bearings so that they won't move.
The strips should be heated using the burner at the central point where the strips touch.
The heat should be conducted from the point of touch of the strips to the ball bearing.
When the heat is transferred along the length of the ball bearing, the wax melts and the ball bearing drops.
We use a time watch to record the time required for the wax to melt on each metal strip and construct a table with the recorded data.
The experiment is then repeated to calculate an average of each time.
As we know, thermal conductivity is the ability of a material to conduct heat. A material with high thermal conductivity will be heated faster than materials with low thermal conductivity. Using the time taken for each strip to fall is used to find which material is the best thermal conductor or had the highest thermal conductivity.
The results are shown below in the table. The metals are ranked based on the time it took for the wax to melt on each strip. The metal with the highest metal conductivity is copper and the metal with the lowest thermal conductivity is iron.
Metals ranked from highest to lowest thermal conductivity |
1. Copper |
2. Aluminium |
3. Brass |
4. Iron |
Factors affecting heat transfer by conduction:
The aim of this experiment is to investigate the rate of convection of potassium permanganate crystals in two different temperatures of water.
Some examples of convection heat transfer are:
Heat is initially transferred from the burner flame to the walls of the beaker by conduction.
Then the water closer to the flame is heated and then expanded. Hence the water becomes less dense and rises to the top of the glass. Meanwhile, the crystals are slowly dissolved and are also moved upwards with the expanding water.
The water at the top of the glass is cooled after a while and becomes denser, causing it to fall to the bottom again.
When liquid is heated it expands, which is known as thermal expansion.
This whole process of the recorded observations is continued. This is what we call heat transfer by convection, as heat is transferred through the liquid.
The crystals follow this path called convection current, where the crystals are rising to the top and then fall to the bottom.
When the process is repeated with cold water, it is observed that the convection current is faster in hot water. Therefore a conclusion can be drawn from the above observations that the higher the temperature of the liquid, the higher the kinetic energy of the molecules. Hence, in the hot water experiment, the molecules of the crystals are dissolved and move faster than in the cold water experiment.
The amount of water in the beaker should be exactly the same.
The burner should have the same flame in both experiments.
The crystals should have the same size.
The aim of the experiment is to investigate whether the amount of infrared radiation absorbed by a surface depends on the physical characteristics of that surface.
Thermal energy transfer from the sun to the earth in the form of ultraviolet light is an example of heat transfer via radiation.
Radiation experiment. Georgia Panagi- StudySmarter Originals
Take repeated readings for each coloured flask.
Read the values on the thermometer at eye level, to avoid parallax error.
Same amounts of hot water.
Same starting temperature of the water.
Same time interval.
There are three main methods for energy transfer: conduction, convection, and radiation.
Conduction is the transfer of thermal energy that is transmitted by collisions between atoms and molecules due to temperature differences.
Convection is the transfer of thermal energy due to the movement of heated fluid. There are two types of convection, namely, natural convection and forced convection.
Radiation is the transfer of thermal energy, in the form of electromagnetic radiation, which is emitted by a heated surface in all directions.
The different types of heat transfer are convection, radiation, and conduction.
Cooking on the stove. There is energy transfer in the form of heat between the thermal energy of the stove and pan.
Four examples of convection are land breeze, sea breeze, refrigerator, and electronic cooling.
Conduction is the most efficient method of heat transfer.
The particles gain energy and break away from one another.
What is thermal energy transfer?
Thermal energy transfer involves the transfer of internal energy or the total amount of kinetic energy and potential energy of all the particles in a system.
What are the main methods of heat transfer?
Convection, conduction, and radiation.
What is conduction?
Conduction is the transfer of thermal energy that is transmitted by collisions between atoms and molecules.
When does conduction occur?
It occurs between two objects that have different temperatures and are in contact.
What is convection?
Convection is the transfer of thermal energy due to movement of heated fluid.
When does convection occur?
When pressure gradient is present in a fluid due to temperature difference.
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