1. TYPES OF THERMOMETERS

2. Liquid Thermometers Most commonly found thermometer
use the “expansion” and “contraction” of a liquid to measure temperature
liquid (usually colored ethyl alcohol) expands when it is warmed up and is forced up the narrow bore of the thermometer
the more it is warmed→ higher it goes
when liquid cools it contracts, dropping lower in bore
Now made primarily of Alcohol instead of Mercury
Range -70C to 78C

3. Parts of the Thermometer
(Bore)

4. Special Clinical Thermometer
has a constriction point that restricts the movement
as body temperature heats liquid it forces it past this point to show temperature
when it’s removed from the patient the liquid can’t move back past the constriction so temperature can be read after it’s taken
must be shaken to return liquid back to bulb
Range: 35C-42C

5. The Thermostat
used to measure temperature in a room or in an appliance
it can also switch appliances on or off at a preset temperature (Feedback system)
Use the expansion and contraction of a solid to measure temperature
have a “BIMETALLIC STRIP”: a strip made of two metals
because the metals are different the expand and contract different amounts causing the strip to bend
the amount of bend is dependent on the temperature
that bend measures the temperature

6. Thermostats- FEEDBACK System
Thermostat for your furnace
Say you want your room to be at 17C, so you set the thermostat
As the temperature in the room rises above 17C the bimetallic strip expands which causes the contact point for the circuit to break away, turning the furnace off
when the the temperature drops back below 17C, the strip contracts, causing the mercury to flow to the contact, completing the circuit, turning the furnace on

7. Thermocouple uses electricity to work
has two wires, made of different metals that are coupled (joined) at one end
when they touch each other it generates electric current
the amount of current depends on the temperature
the other ends of the wire are connected to a meter that measures electricity
the amount of electricity measures the temperature
used in very extreme temperatures (higher than a standard thermometer)
Range: C

8. Other Thermometers
Recording Thermometer: A bimetallic strip connected to a writing device and paper which records temperature fluctuations over time.
Infrared Thermogram: Records infrared radiation, (heat sensor) as different colors according to their temperature.

9. Measuring Devices
Each device we’ve looked at has a sensor (something that is affected by changes in the environment)
the sensor produces a signal (information about temperature, such as electrical current) that affects a responder (a pointer, a light, or other mechanism that transmits the signal in some way)

10. Types of Thermometer Worksheet
Complete the worksheet, put your name on it, put it in the pass-in bin
go to Google Classroom and respond to the exit slip question