Thermometers

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Thermometers
-a mechanical or electrical device for measuring
temperature
REMEMBER temperature is the AVERAGE speed of the
particles!
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Temperature Scales
Farhrenheit



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The Right Device for the Job
-a regular laboratory thermometer is not always
the best device to use
Ex. Lab Thermometers have a scale that goes from
-20 degrees Celsius to 110 degrees Celsius

• In what situations would this pose a problem?

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-thermometers have been developed to suit almost
every purpose
-most thermometers have these three parts
i) SENSOR a material which is affected by the
change in temperature ex. water
gets heated
ii) -the sensor produces a SIGNAL information
about the temperature ex. water
rising up/down the tube
iii) -the signal affects a RESPONDER light,
pointer, or other mechanism that use the signal

ex. water is read on the scale
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Four Types of Thermometers

• not all thermometers are created equal

• Some have different properties that allow them to
  work better than others under certain conditions

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1. THERMOCOUPLE

• two different metals (usually copper and iron)
  that are twisted together

• when the metals are heated, a small amount of
  current electricity is produced

• the larger the current of electricity, the hotter
  the temperature!

USES -measuring very high
temperatures -stoves, furnaces
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2. BIMETALLIC STRIPS
-relies on the fact that different metals expand
at different rates as they warm up.
-by bonding two different metals together, you
can make a simple electric controller that can
withstand fairly high temperatures. This sort of
controller is often found in ovens.
By bonding two different metals together, you can
make a simple electric controller that can
withstand fairly high temperatures. This sort of
controller is often found in ovens.
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3. RECORDING THERMOMETER
-records the temperature of an area over a long
period of time
-a pen, connected to a bimetallic strip, records
the temp on a rotating drum
-as the bimetallic strip flexes, it moves the
needle up or down based on the paper
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-can be used to measure temp over days,
weeks, even years!!
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4. INFRARED THERMOGRAMS
-a device (camera) that measures the amount of
radiant energy given off by an object
-can tell the temperature of an object from a
great distance away
-hotter objects - yellows, reds and whites
-colder objects blues, purple, and black
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Used for
Identifying where houses are losing heat
Finding where motorized parts are overheating
Where electrical devices have a short
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Identifying weather patterns
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Exploring outer space.
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Can you spot the person in this picture who has
the flu?