Convection, Conduction & Radiation Flashcards
What are good conductors of heat? and what does that mean?
-Metals are good conductors of heat
-Materials that efficiently transfer heat
What are bad conductors of heat? and what does that mean?
-Non metals, liquids and gasses
-Bad conductors prevent energy transfer by conduction
What is an example of both a good and bad conductor?
-A towel is a bad conductor and prevents heat energy transfer
-The bathroom floor is a good conductor of energy and heat energy is conducted to the floor
How does conduction work?
When heated, atoms vibrate more, as they do they bump into eachother and transfer energy from one to another
Why is metal such a good conductor of heat?
The delocalised electrons can collide with the atoms, helping to transfer the vibrations and therefore transfering heat better
Why do materials containing air pockets act as such a bad conductor of heat?
-The air is trapped, and thus can’t move to make a convection current.
-therefore energy transfer by conduction occurs.
- But this happens very slowly because air is a gas and a poor conductor of heat
Describe what how a convection current occurs.
-When a liquid or gas is heated
-The molecules push eachother apart, making the fluid expand
-This makes the hot fluid less dense than its surroundings
-The hot fluid rises and the cooler surrounding fluid takes its place
-Eventually the hot fluid cools, contracts and sinks back down again
What is the relation between heat and infared radiation emitted?
The hotter the object is, the more it radiates at a given time
Describe the convection, conduction and radiation of a hot coffee mug.
-Energy is transferred from the surface of the mug to its surroundings, due to the infared radiation being emitted from its surface
-Energy is transferred by heating as the most energetic particles evaporate at the top of the coffee mug, creating a convection current
-Energy is transferred by heating through conduction to any surface the mug is in contact with
