Thermal Physics Flashcards
How do you reduce heat loss in homes?
- Plastic foam lagging around the hot water storage tank
- Double glazing
- Glass or mineral wool insulation in the loft
- Wall cavity filled with plastic foam, beads or mineral wool
How do metals conduct electricity?
- Atoms heat up and gain kinetic energy, so move faster.
- Atoms collide with neighbouring atoms and make them vibrate faster.
- This transfers heat.
- Delocalised electrons heat up and gain kinetic energy, so they move faster.
- Delocalised electrons collide with atoms and make them vibrate faster.
- This transfers more heat.
Describe an experiment to show that black surfaces are better emitters of heat and describe control variables.
Fill metal cube with boiling water with different surfaces on it.
Place a thermal radiation detector away from the surfaces.
Heat the surfaces to the same temperature.
1. Heated to same temperature
2. Radiant heater same distance from each surface.
Describe an experiment to show that black surfaces are better absorbers of heat.
Apparatus: radiant heater, thermometers, black and white cans
Actions: Fill cans with water. Place at equal distances from the radiant heater. Measure temperature rise.
Observation: Water in black can as greater temperature rise.
What is internal energy?
Kinetic energy of particle + potential energy
To remember when drawing Brownian motion
- Some paths longer than other
2. Some paths cross
What is the ice point?
When pure water melts
What is the steam point?
When pure water evaporates at standard atm
What is temperature?
Measure of average energy of molecular motion in substance
Is a solid the only thing that conducts?
No, everything conducts - including air. But air is a poor conductor.
Why do both sides (matt black and polished) of a copper sheet cool to the same temperature?
Because conduction also takes place, and copper is a good conductor so conduction is rapid and heat flows equalises the temperature.
