TYPES OF THERMOMETERS
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
Parts of the Thermometer (Bore)
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
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
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 https://www.youtube.com/watch?v=q0rQb4gAtrs
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: 0-1700C
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.
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)
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