Unit 1: C1 Heat Flashcards
what is Air Temperature
A measure of how hot or cold the air is
How is temperature expressed
In Degrees Celsius
What is typical room temperature
20-25 Degrees
What is the scientific way to describe temperature
- Degrees Kelvin
2. 0 kelvin is equal to 273 degrees Celsius
what instrument is used to measure air temperature
thermometer
What is thermal radiation
Heat that radiates from a warm object
What are examples of radiant heat sources ?
- The sun
- Fire
- ovens
- kiln walls
5, dryers
6, hot surfaces nad machinery
What is mean radiant temperature
Average surface temperature of surfaces enclosing a space
How can radiant heat be assessed
Using a globe thermometer and the reading is known as a globe temperature
what is humidity
the amount of water vapour present in the air
Why is humidity in our homes bad?
- Because it causes mould, moisture and creates condensation on our windows
- High humidity influences homes and health
- low humidity helps spread the rate of infection
Humidity chart
>70% poor high humidity levels >60% and <70% fair >30% and <60% maintain your healthy levels >25% and <30% fair <25% poor low humidity levels
Higher temperature leads to high humidity
When does humidity change
- Atmosphere gains or losses water vapor
- Evaporation
- Temperature changes
- Lower temperature - relative humidity changes
- Raise temperature - relative humidity decreases
what does a whirling hygrometer measure
- Humidity
2. heat
What is air velocity / movement
The speed of air moving
What are the effects of still/stagnant air
If artificially heated may cause people to feel stuffy
What are the effects of air movements in cool or cold environments
Draught
What instrument measures air movement
Anemometer
or
kata thermometer (measure time it takes for air too cool)
Explain one way a thermostat controls temperature
- The thermostat measures the temperature of the air (1) therefore interprets the information to turn on/off heating system (1)
- Thermostats can contain a heat activated switch (1) which opens and closes a circuit to control heat
What are factors that can affect human comfort
- Metabolism
- Clothing insulation
- Gender