HEAT ENERGY AND ITS TRANSFER 1
Learning Points State that heat flows through a solid by conduction. Explain conduction in terms of vibrating particles. Know that metals are good conductors of heat energy. 2
Learning Points 4. State that a material which lets heat flow through it easily is a good conductor of heat 5. State that a material which does not let heat flow through it easily by conduction is an insulator of heat. 3
HEAT TRANFER BY CONDUCTION 4
Conduction When heat travels by Conduction, the particles near the heat source start to vibrate. These vibrations are then passed to the atom next to them, which in turn pass the vibration through the material. 5
Heat Energy Conductors Metals are very good conductors of heat, which is why a metal spoon will get hot very quickly when used to stir the contents of a pan. 6
Quick conduction experiments Step up a clamp stand with four paperclips stuck onto a metal rod with vaseline. 2. Heat one end of the rod and time how long the paperclips take to drop off. www.abernet.org.uk 7
TIME TAKEN TO FALL OFF (S) Quick conduction experiments PAPERCLIP NUMBER TIME TAKEN TO FALL OFF (S) 1 2 3 4 8
Quick conduction experiments The heat from the bunsen burner has travelled along the rod by conduction. Can you explain what happened to the metal particles (or atoms) to allow the heat to move through the rod? 9
Conduction and Particles 10
What is the best conductor? Place two different metal rods on a tripod stand so that they are touching at one end. 2. Stick a paperclip on the end of each rod using vaseline. 3. Heat the end of the rods that where they meet and time how long the paperclips take to drop off. www.abernet.org.uk 11
TIME TAKEN TO FALL OFF (S) What is the best conductor? TYPE OF METAL ROD TIME TAKEN TO FALL OFF (S) 12
What is the best conductor? The heat from the bunsen burner has travelled along both the rods by conduction. Can you explain why the conduction was faster in one rod and slower in the other? 13
Good conductors in the home Stainless steel (mostly Iron) is a very good conductor of heat and is used to make cooking pots. Can you think of any other items in your home that are good conductors? 14
HEAT ENERGY INSULATORS Wood is a poor conductor of heat. We tend to use wooden spoons in cooking since they won’t pass the heat through them onto your hand. We call Wood a good INSULATOR. kitchenaria.com 15
What is the best insulator? Place three different rods (metal, plastic and wood) into a beaker containing freshly boiled water. 2. After 5 minutes GENTLY touch the end of each rod and find out which ones are hot or cold. www.abernet.org.uk 16
HOT OR COLD AFTER 5 MINUTES What is the best insulator? TYPE OF METAL ROD HOT OR COLD AFTER 5 MINUTES 17
What is the best insulator? The heat from the bunsen burner has NOT travelled along some of the rods. Can you explain what happened to the particles in the INSULATORS that didn’t allow the heat to move through them? 18
Quick Quiz What is temperature a measure of? How can you make the temperature rise? What is the difference between “heat” and “temperature”? How hot or cold something is. Add heat energy Heat is the energy, temperature is how hot or cold something is. 19
Put these statements in order The neighbouring particles also move. Heat makes the particles vibrate. Particles in a solid are tightly packed together, so The heat can therefore travel along the solid. This movement means they have a higher temperature. 3 1 2 5 4 20
Fill in with “well” or “badly” A conductor lets heat travel _______. An insulator lets heat travel _______. Air lets heat travel _______ by conduction. well badly badly 21
Answer the questions Examples of conductors in the home are: Examples of insulators in the home are: Electric Iron, saucepan Pot handles, clothes 22