P2 Flashcards
The higher the thermal conductivity of a material, the ____ the rate of energy transfer by conduction across the material
Higher
What is thermal conductivity?
A measure of how well a material conducts electricity when heated
What does the energy transfer per second through a layer of Insulation material depend on?
- temperature difference across material
- thickness of material
- thermal conductivity of material
The larger the temperature difference the ____ the rate of energy transfer by conduction
Higher
The ____ the material, the lower the rate of energy transfer by conduction
Thicker
How can you reduce energy loss in homes?
- loft insulation
- cavity wall insulation
- double glazing
- draft excluders
Insulation traps air in small pockets, reducing rate of energy transfer by conduction.
How can we reduce the cost of producing energy in the home?
- energy efficient boiler
- install solar panels
What is the specific heat capacity of a substance?
The amount of energy required to raise the temperature of 1kg of the substance by 1°C
Describe the specific heat capacity RP
- Measure mass of block
- Measure start temperature of the block using a thermometer
- Turn on powerpack, and increase temperature of block using an immersion heater
- Measure energy input using a Joulemeter
- Record end temperature and calculate the temperature difference
- Find specific heat capacity
How can you improve the specific heat capacity rp?
- Wrap block in insulation to minimise heat loss
- Repeat investigation to calculate an average and reduce error
Some students want to investigate the effectiveness of different materials as thermal insulators. What is the IV, DV and CV?
IV- material
DV- Temperature change
CV- Thickness of material, volume and temperature of water, time allowed for water to cool
Some students want to investigate the effectiveness of different materials as thermal insulators. Suggest a method for them to follow
- Cover container in insulating material
- Pour 200ml of water into container using a measuring cylinder
- measure start temperature with a thermometer
- time 10 mins
- measure end temperature and calculate the difference
- repeat for the other materials
Some students want to investigate how the thickness of a material effects the rate of energy transfer. What is the IV, DV and CV?
IV- Thickness
DV- Temperature change
CV- Material, volume and temperature of water, time allowed to cool
Some students want to investigate how the thickness of a material effects the rate of energy transfer. Suggest a method for them to follow
- Cover container in 1 layer of insulating material
- Pour 200ml of water into container using a measuring cylinder
- measure start temperature with a thermometer
- Record temperature every 30 secs for 10 minutes using a stopwatch
- Repeat for 2,3,4,5 layers of insulating material
What do the thermal insulation results show?
the thicker the material, the slower the rate of energy transfer from container
What is the equation for specific heat capacity?
change in thermal energy (J) = mass (kg) x specific heat capacity (J/kg degree C) x change in temperature (degrees C)
