HEAT Flashcards
WHAT IS THE SPECIFIC HEAT CAPACITY?
Amount of energy needed to raise temperature of 1kg of a substance by 1degree C.
The bigger the SHC the more energy needed to change the temp of each degree.
They greater the mass the more energy required.
WHAT IS LATENT HEAT?
SPECIFIC LATENT HEAT OF FUSION?
SPECIFIC LATENT HEAT OF VAPORISATION?
Energy supplies in the change of state. Measured in J/KG
Energy needed to melt.
Energy needed to change a substance at its BP from liquid to vapour.
WHAT IS INFRA RED
The thermal radiation given off my an object . Measured by an infra red detector.
BEST ABSORBER OF RADIATION?
Dark, matte.
BEST EMIITTERS
Dark, matte. Black transfer energy quickly.
BEST CONDUCTOR?
Shiny
BEST REFLECTOR?
Shiny white
WHAT SIZE IS BEST FOR RADIATING?
Large surface area
HOW TO INCREASE THE RATE OF ENERGY TRANSFERRED?
The great her the difference between the object and its surroundings
WHAT IS CONVECTION
In liquids and gas
Fluid heated - expands and particles move further apart making it less dense so it rises. Warm fluid is replaced with cooler more dense fluid which results in a current.
WHAT IS EVAPORATION?
When a liquid turns to gas. More energetic particles escape from liquid and enter the air. Average kinetic energy of particles left is less so the temperature decreases - cooling.
Increase surface area and temperature to increase rate.
WHAT IS CONDENSATION?
When gas turns to liquid.
Increase surface area and reduce the surface temperature.
WHAT IS CONDUCTION?
Mostly in solids as liquids and gases are poor conductors. Metals are good conductors. One end heated particles gain kinetic energy and vibrate more - pass energy to neighbouring particles. Metals have a free electron which can gain kinetic energy and move through metal colliding with other particles. Happens in non metals too.
HOW TO IMPROVE EFFICIENCY
Minimise the wasted energy.
WHAT IS ENERGY CONSERVATION?
Energy at the start is the same as the end.
