The Kelvin Scale After the creation of the Celsius scale the Kelvin scale was created because new gases were being discovered Scientists required a more accurate reading of high and low temperatures ID: 779559
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Slide1
Topic 2 Part 2 – Devices for measuring temperature
Slide2The Kelvin Scale
After the creation of the Celsius scale, the
Kelvin scale
was created because new gases were being discovered. Scientists required a more accurate reading of high and low temperatures.
Slide3Absolute Zero
Absolute zero
is the coldest possible temperature
Absolute zero on the Celsius scale is -273.15oC
Absolute zero on the Kelvin scale is
0 K
Slide4What is the difference between heat and temperature
Heat
is a measure of energy of the particles moving around
Thermal Energy is HEAT!
Temperature
is a measure of how hot or cold something is measured on a scale like a thermometer.
Slide5Different thermometers have been developed over time
They suit different purposes:
Slide6How does a thermometer work?
Explain in general how a thermometer works using the terms
sensor
, signal and responder.Page 199
Sensor
: a material which responds to temperature change (
ie
: alcohol)
Signal
: Information about the temperature (
ie
: scale)
Responder
: A pointer, light or other mechanism that uses the signal (
ie
: level alcohol reaches)
Slide7Slide8Video: Eurika Science!
Eurika
! heat vs. temperature
Slide9Thermocouple
Description
- wires of two different metals are twisted together (copper and iron)
- when heated it produces an electrical current
Use
- turn switch on or off it temperature changes
Reason for Development
- measures high temperatures
- cannot be used to measure
low temperatures
Slide10Slide11Bimetallic Strip
Description
- two metals fused together
- expands at different rates- coils when heated - reverses when coolsUse
- operates electrical switches
- controls furnace (
thermostat
), air conditioner, fridge
Reason for Development
- easy way to turn something on and off automatically
Slide12Slide13Slide14Recording Thermometer
Description
- a
bimetallic strip joined to a lever with a penUse
- records small movement of temperature change
- weather records
Reason for Development
- records temperature over a period of a week
Slide15Slide16Infrared Thermogram
Description
electronic
sensor or device that photographs temperature change through colourphotographs
radiation
Use
detects
air leaks
energy
efficient
can
be used to predict dangers of over heating
Reason for Development
detects
precise temperature change - not visible to the eye
quick
and accurate
Slide17Slide18Slide19To measure temperature
1. Thermometer
2. Thermocouple
3. Bimetallic Strip4. Recording Thermometer5. Infrared Thermogram
Slide20Eurika Science!
Eurika
: Measuring Temperature
Slide21Thinking time!
Which tool for measuring and controlling temperature would be most affective?
1. Controlling an electric frying pan?
2. Making long term records at the weather office?3. Detecting small forest fires before they spread?
Slide22Controlling a fry pan
bimetallic strip
Slide23Long term records
Recording Thermometer
Slide24Forest Fire
Infrared
Thermogram