Thermal Physics Flashcards
Explain about the Bonds in Solids
Solids have strong intermolecular forces, which prevent the molecules from moving.
Explain about the Bonds in Liquids
Liquid Molecules have enough energy to break bonds between them. The Bonds are still there, but don’t hold the molecules in place, so they can slide past each other, allowing liquid to flow.
Explain about the Bonds in Gasses
Gasses move randomly due to no long range forces holding the molecules together, so the molecules move freely, allowing gasses to move freely. Gasses can be compressed due to the large spaces between the molecules.
What is Brownian Motion
Brownian Motion is the random movement of particles, as they hit air particles, causing them to change direction randomly.
What are Differences between Evaporation and Boiling?
Evaporation happens at any temperature, and only on the surface of the liquid, while Boiling happens at a fixed temperature, and on the whole liquid.
When does Evaporation happen?
Evaporation Happens when surface molecules have enough energy to break the bonds and escape.
What Effect does evaporation have on the Remaining Liquid?
The Temperature of the Remaining Liquid will also decrease, while the average energy of the remaining liquid will also decrease.
If an Object is in contact with an evaporating liquid, as the liquid cools, the object cools too.
What Factors Impact the Rate of Evaporation?
1) Temperature
2) Surface Area
3) The Movement of Air across the surface area of the liquid.
What Increases Pressure of a Gas?
1) Increasing the Temperature
2) Reducing Volume
What is Boyles Law ?
Boyles Law states that if the temperature remains constant, the Final Pressure and volume will be equal -> P1V1 = P2V2
What is Thermal Expansion?
Thermal Expansion is when the temperature increases, so the particles vibrate faster, causing them to knock into each other and move apart.
What are Uses of Thermal Expansion?
1) Thermometer
2) Bimetallic Strip consisting of 2 Different Metals can be made to bend at a given temperature forming a temperature activated switch.
What are Consequences of Thermal Expansion?
Thermal Expansion can cause Solid Objects to buckle if they get too Hot, such as roads- so space is built.
What are the Steps to build a Thermometer?
1) Identify Fixed Points ( where easily identifiable change occurs )
2) Measuring a Property allows you to find its values at other Temperatures
3) Sensitivity - If the Object changes significantly with temperature, its easier to detect
4) Range - If too short, there may not be enough room for Liquid to expand to
What are Liquid in Glass Thermometers ?
Liquid in Glass Thermometers consist of Thin Glass Capillary Tubes, with a glass bulb at one end which contains large volume of liquids which, when heated, expand into the glass tube, and a scale on the side which allows the liquid to be measured.
What are Properties of the Liquid in Liquid in Glass Thermometers?
1) Expand Linearly with Temperature
2) Expand Significantly- greater sensitivity
3) Low Freezing Points/ High Boiling Points- Wide Range
How to increase the Sensitivity of Liquid in Glass Thermometers ?
1) Smaller Glass Bulb
2) Narrower Capillary Tube
3) Glass Bulb with Thinner Wall
What is a Thermocouple?
Thermocouples consist of 2 Dissimilar wires attached together.
How does a Thermocouple Work?
Thermocouples consist of 2 Wires Joined together. When the Junction between the 2 Wires is Heated, a voltage is created between the 2 wires
The Greater the Temperature, the Greater the Potential Difference ( Voltage ). However, they are not as sensitive as Liquid in Glass Thermometers, but due to the High Melting Point of the Metals, they can measure high temperatures can be measured. Thermocouples are also very responsive to changes in Temperature.
