Heat Energy and Transfer
Heat and Temperature are things that everyone is familiar with. They are also something that in everyday language, may not match the science explanation.
The following is the science definition for:-
Heat - Heat is a type of Energy, it is measured in Joules (J).
Temperature - Temperature is a measure of how hot or cold an object is, it is measured in °C.
The diagram below shows an example of why temperature is not always the best way to understand heat:-
Note - Sparklers are dangerous. Even though each spark has only a small amount of heat Energy, the sparkler itself can cause serious burns or start fires. Sparklers are classed as fireworks and as such are illegal to buy if under 18 under the Fireworks Act 2003. They should only be used in direct adult supervision.
Heat Energy does not stay in one place, but will move from place with lots of heat Energy to places with less. This is why a cup of coffee will cool down over time, and why ice cream melts on a hot day.
There are three main types of heat transfer:-
Conduction - Heat moving through a solid, by causing particles to vibrate more.
Convection - Heat moving through a liquid moving in a convection current.
Radiation - Heat moving as electromagnetic radiation (Infra-Red Radiation).
When Iron is heated in a blacksmith's furnace, the Iron starts to glow, first a dull red, then becoming a brighter yellow colour. This happens even in parts of the metal bar that is not in the furnace. Somehow, the heat Energy can travel through the metal. Eventually, the blacksmith would burn their hand!
The video below shows a blacksmith heating metal to forge a sword.
In the video above, the metal turned red in parts that had not been in the furnace. This means that the heat Energy was moving through the metal. The blacksmith must wear protective gloves as even though parts of the metal are not hot enough to glow, the whole bar will soon become very hot. This is because of the heat transfer process called Conduction.
The diagram below shows how heat Energy can be transferred by Conduction:-
The molecules that make up a metal bar (or any solid) are tightly packed together, vibrating around a fixed point. When one end is heated, it makes the molecules vibrate more. This causes the molecules next to these to vibrate more, and so on, transferring the heat Energy along the bar. This is called Conduction.
As a Blacksmith, you would shape heated metal into practical and decorative objects including gates, railings, furniture, tools and horseshoes.
You’d heat a piece of a metal such as steel, iron, brass, copper or bronze in a very hot fire until it is soft and workable. You’d then hammer, bend, cut and join the hot metal before it cools and hardens.
You could specialise in industrial work and make items such as specialist tools, fire escapes or security grills.
Or you could produce artistic or architectural metalwork such as decorative ironwork, gates, sculptures and furniture. You’d either make your own designs or create pieces based on instructions from clients.
A Career as a Blacksmith
Salary: from £15,000 to £30,000 per year
Blacksmith working hours: 35 and 40 hours a week, Monday to Friday. You would often be self-employed or work in a small business, so your hours would depend on your workload.
Typical entry requirements:You can learn on the job, completing a work-based qualification such as a Modern Apprenticeship. Or you can complete a National Certificate (SCQF level 2-6) or Higher National Certificate (SCQF level 7) in Fabrication and Welding.
To enter a Fabrication & Welding National Certificate/National Qualification may require no formal entry qualifications but most courses ask for National 4/5 qualifications and may involve an aptitude test.
To enter a Higher National Certificate (SCQF level 7) requires National 5 qualifications and one to two Highers.
Attention to detail
Developing a plan
Conductors and Insulators
Metals are good conductors of heat Energy. This means that heat Energy easily can move through a metal (as described above). Not all materials let heat Energy move through them easily, however. Materials which do not let heat Energy move through them easily are called Insulators.
Substances that allow heat Energy to pass through them easily are called Conductors.
Substances that do not allow heat Energy to pass through them easily are called Insulators.
The table below shows some examples of Conductors and Insulators:-
In a solid, the molecules are close enough together for heat Energy to be passed from atom to atom, but this is not the case in liquids and gases. As the molecules can move around, there is another way to transfer heat Energy, known as Convection.
The diagram below shows the process of Convection:-
When a fluid (a liquid or a gas) is heated, it becomes less dense. As it is now less dense than the fluid around it, the warm fluid rises. As it rises it begins to cool and become more dense, eventually sinking back down. This causes a convection current in the fluid.
Examples of Convection
Convection currents can be found anywhere there is a fluid that is being heated. Some examples include:-
Central heating within the home.