1
Q
Describe the practical used to determine the Specific Heat Capacity of a material
A
1.Select your material (e.g. copper or aluminium) and measure its mass using a mass balance
- . Wrap an insulator with a low thermal conducivity around the block
- Using a thermometer, measure the initial temperature of the block
- Place an immersion heater into the larger hole in the block ( add a few drops of water to** fill any gaps** in order to improve the thermal energy transfer between the heating element and the block)
- Connect ammeter and power pack in series with the heater and a voltmeter in parallel with the power pack
- Turn power pack on to 12V, start stop watch at the same time
- Record ammeter and voltmeter readings every 60 seconds
- After 10 mins, turn power pack off
- Keep thermometer in the metal block for a while longer and record maximum teperature of metal block
- Use various voltage and current readings to calculate the power output every 60 seconds (P = I x V )
- Use power outputs and the times to** calculate** the energy (E = P x t )
- Plot a graph of the resultswith temp. change on the** y-axis** and energy transferred on the** x-axis. The specific heat capacity** can be found by doing 1/mass x gradient
2
Q
State the sources of inaccuracy in the SHC practical and how they can be fixed
A
- Themral energy dissipating into surroundings = wrap with an insulator that has a low thermal conductivity
- Incorrectly reading thermometer= use an electric temperature probe
- (with water) the thermal energy may not be distributed evenly= stir the water
3
Q
Describe the Thermal Insulation practical
A
- Set up 6 beakers, with 0,1,2,3,4, and 5 layers of insulation material around each beaker
- Use an electric kettle to boil water, and pour 200cm cubed of the water in the beaker
- Use a piece of cardboard with a hole in it as a lid for the beaker
- Place a thermometer into the hole in the cardboard, making to sure it is properly immersed in the water
- Measure the initial temperature of water and record it in a table
- Start the stopwatch
- Record temperature every 5 minutes on a table
- Continue for 20 minutes
- Repeat previous steps for each of the different beakers
- Draw a cooling curve graph of the results by plotting temperature agaisnt time for each different number of layers of insulation. The graph with the slowest time is the most effective thermal insulator
4
Q
Whst is the independant variable in the thermal insulation practical?
A
The number of layers of insulation
5
Q
What is the dependant variable in the thermal insulation practical?
A
The temperature
6
Q
What are the control variables in the thermal insulation practical?
A
The initial temperature of the water
The volume of the water
Energy
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