Energy Transfer by Heating Flashcards
What is conduction of heat energy?
The process where vibrating particles pass on their extra kinetic energy to neighbouring particles
When does conduction usually happen faster?
In denser solids
Why does conduction happens faster in denser solids?
Particles are closer together, so they collide more often and pass energy between them
What type of structure does an insulator have?
Larger spaces between their particles, so they conduct heat energy more slowly
What makes metals good conductors?
Free (delocalised) electrons
At the hotter end of a piece of metal, what are electrons doing?
Moving faster and colliding with other free electrons- transferring energy
How does heat energy move from the hot end of metal to the cool end?
By electrons colliding and transferring energy
In which states of matter does convection occur?
Liquids and gases- FLUIDS
What is convection?
When more energetic particles move from hotter regions to cooler regions, taking their heat energy with them
Name 3 appliances that convection is used in
Kettles, hot water tanks, convector heaters (all have an immersion heater)
What is heat energy transferred from in an immersion heater?
The heater coils
When the water particles in an immersion heater get more energy, what do they do?
Move around faster, meaning there’s more distance between them- so the water expands and becomes less dense
What does the hotter, less dense water rise above?
The cooler, denser water
What does the cooler, denser water do?
Get heated by the coils- giving it energy
What are convection current all about?
Changes in density
What is condensation?
Is when a gas cools, causing the particles to lose kinetic energy, and the attractive forces between particles increases, forming a liquid
What’s evaporation?
When particles escape from a liquid
When can particles in a liquid evaporate?
When they travel in the right direction, and if they are travelling fast enough (KE) to overcome the attractive forces of other particles
Which particles are most likely to evaporate?
Fastest ones, they have the most kinetic energy
When particles evaporate, what happens to the average speed and kinetic energy of the remaining particles?
It decreases
When is the cooling effect caused by evaporation useful?
When you sweat, it evaporates and cools you
What does the decrease in average particle energy cause?
Temperature to decrease
What 4 factors effect the rate of evaporation?
Temperature, density, surface area, airflow over the liquid
How does a higher temperature increase the rate of evaporation?
Average particle energy is higher, more have the energy to escape
