Overall Learning Goals:
- To examine how thermometers function
- To practice how to use thermometers properly in order to make careful measurements of temperature
- To investigate the temperatures of water and recognize how temperature is not constant (can change)
2.3 Measuring Temperatures (pg.12-13)
Video Introduction
What is Temperature?
How to Read a Thermometer Properly
- Measure of the average energy of motion of the particles within a substance
- A quantitative measure of how hot or cold an object is
- Result of how fast or slow the particles of a substance are moving
- Causes substances to expand or contract
Today's Activity
1) Hold the thermometer CAREFULLY!
2) Place it in the object and leave it for an appropriate length of time
3) Observe the scale at eye level
4) DO NOT hold it by the bulb
5) Read the temperature to the closest line when it has stopped rising or dropping and record
Learning Goals:
- To use a thermometer properly to make careful measurements of temperature
- To investigate the temperatures of water and recognize how temperature is not constant (can change)
Instructions:
In partners or groups of 3, you will need a thermometer, a beaker for water and ice cubes
1) Fill the beaker with cold water and predict the temp. in the table found on your worksheet
2) Then, place the thermometer in the beaker and record the actual temperature of the water
3) After everyone in your group has recorded the temperature, remove the thermometer, put an ice cube in the beaker and record the temperature of the water with the thermometer after one minute
4) Bring back your beaker to be filled with hot water and repeat the steps above
*Make sure you record your observations for both cold and hot water in the table
*Answer the questions and complete the thermometer diagrams on your worksheet *Hand in ASAP!
*Make sure you label, colour, and don't forget to write the numbers for the scale
Why do we need to measure temperature?!
The Thermocouple
Motion of Particles and Temperature
- Uses electricity to operate and is useful for measuring very high temperatures in places where people cannot go such as a blast furnace
- Contains two wires, each of a different metal, that are joined (coupled) at one end
- When the two different metals touch each other, a tiny electrical current is generated
- The amount of electricity depends on the temperature
- The other ends of the wires are connected to a meter that measures electricity so by measuring the amount of electricity from the meter, the temperature of the metal wires can be measured
This relates to how thermometers operate!
The Thermostat
What part of the thermometer does this?
- Expansion – an increase in the volume of an object or substance.
- If you add heat, the substance will expand.
- Contraction – a decrease in volume.
- Occurs when heat is removed from an object or substance.
- Used to measure temperature in a room or in an appliance i.e. a furnace
- Uses the expansion and contraction of solids to measure temperature
- Contain a strip made of two metals (bimetallic strip)
- When heated or cooled, the two metals expand and contract by different amounts, causing the strip to bend
- The amount of bending depends on the temperature
- This provides a measure of the temperature
Outdoor Thermometer
Clinical Thermometer
- Type of thermometer that is typically used to measure body temperature
- Sensitive to very small changes in temperature
- Has a constriction area that stops the liquid from moving back unless you shake the thermometer downward (lets you read the temperature long after it is taken)
Liquid Thermometers
Outdoor Thermometers
- These thermometers use the expansion and contraction of a liquid to measure temperature
- Liquid in the bulb (colored ethyl alcohol) expands when it is warmed and is forced up the narrow bore of the thermometer.
- As liquid cools, it contracts causing it to decrease within the bore
- Increase in heat = higher it rises
- Decrease in heat = lower it drops