Physics core practicals - Paper 1
Specific heat capacity
Method
Record the mass of the object you want to find the SHC for
Place an immersion heater into it, and a thermometer
Record the starting temperature and wrap the material in insulation
Connect the immersion heat to a circuit and joulemeter
Leave this set up for 20 minutes
Read the total temperature that has been transferred to the immersion heater, and the final temperature of the oil
Calculation
Place the variables in the arranged equaiton for SHC
Once you've done that you have a value for SHC
Inaccuracy
Thermal energy transferred to surroundings, you need to use a material with a low thermal conductivity
Not all energy from emersion heater transfers from the material, make sure the immersion heater is submerged
Incorrect reading on the thermometer, use an electronic temperature probe
Thermal insulators
Materials
Method
Pour some boiling water into a beaker
Place a lid on top with a hole for the termometer
Record the starting temperature of the water
Record the temperature at set intervals
Repeat the experiment using different materials, make sure to use the same mass of material
Variables
Independent - insulating materials
dependent - temperature
Control - volume of water, mass of insulation
Thickness of material
Method
Start with a beaker containing hot water
Place a thermometer through a lid on top
Measure the temperature of the water at set intervals
Repeat the experiment using different layers of a materials
Variables
Independent - layers of insulation
Dependent - temperature
Control - starting temperature of water and volume
I/V characteristics
Method
Connect a component to a circuit, connect the voltmeter in parallel and an ammeter in series aswell as a variable resistor
Read the current and pd through the component
Adjust the variable resistor and record a new reading
Do this several times
Switch the direction of the battery and repeat
Plot a graph of Current against voltage
Try this with a resistor, filament lamps and a dioide
Problems
Temperature will increase the results
Density
Regular objects
Calculate the volume using dimensions using a ruler
Calculate the mass using a balance
Density = mass/volume (use this equaiton)
Irregular objects
Calculate the mass uisng a balance
Use a eureka can to calculate the volume of water the object displaces, this is equal to the volume of the object
Density = mass/volume
Core practical : factors affecting resistance
Problems
If the temperature increases, so does resistance - to solve this use low pds and only turn on the current when taking a reading
You can never get the crocodile clip at zero, this is a zero error
Resistance is a circuit can depend on a number of factors , like whether the components are in series or parallel, or the length of wire used in the circuit
Results
If you used two wires with different thickness, then you should find that the thinner wire produced a greater resistance
The longer the wire, the greater the resistance
You should find that the data is in a straight line, meaning that the resistance is directly proportional to the length
Method
Plot a graph, with resistance on the y axis, and wire length on the x
Once you have a good amount of data (10cm-100cm) then calculate the resistance using the equation R = V / I
Turn off the power, so the wire doesn't overheat, while you adjust the length of the wire
Once the circuit is set up, begin the experiment, by turning on the power pack, making sure it is at a fixed reading throughout, and recording the current and pd
Attach another slip, which can be moved throughout the experiment, so you can investigate the resistance at different lengths
Attach a crocodile clip to the wire at the 0cm positions
Set up a circuit, with an ammeter in series with a meter ruler, and a voltmeter in parallel with the ruler