Paper 1 required practicals Flashcards
Insulation PAG - If you want to investigate the effectiveness of different materials as insulators state the variables and whether they are continuous, discrete or cateroric
Independent - type of material - catergoric
Dependent - temperature loss - continuous
Controls - Volume(continuous), starting temperature(continuous), thickness of insulating material (continuous)
Insulation PAG - If you want to investigate the effectiveness of different materials as insulators state what type of graph you would draw and why?
Bar chart - one of the variables is catergoric
Insulation PAG - If you want to investigate the effectiveness of different materials as insulators describe a suitable method
- Boil a kettle and measure a set volume of boiling water in a measuring cylinder.
- Pour this boiling water into a beaker and wrap with a particular type of insulator
- Use a thermometer to measure the initial temperature
- Use a stop clock to time for 10 minutes and then measure the final temperature.
- Calculate the temperature change (Initial temp - final temp)
- Repeat to calculate an average
- Repeat for all the different insulators making sure the starting temperature and volume are controlled.
Insulation PAG - If you want to investigate the effectiveness of different materials as insulators describe what would cause errors in the experiment and how they would be reduced.
Heat lost to the surrounding, place a lid on top of the beaker.
Insulation PAG - If you want to investigate how the thickness of an insulator affects the rate of heat loss state the variables and whether they are continuous, discrete and catergoric
Independent - Number of layers of insulation - discrete
Dependent - temperature loss - continuous
Controls - Volume(continuous), starting temperature (continuous), type of insulation (categoric)
Density PAG - how can the density of a regular shape be found?
Measure the mass using an electronic balance
Measure the length of each side using a ruler
Calculate volume (length x breadth x width)
Calculate Density (mass / volume)
Density PAG - how can the density of a irregular shape be found?
Measure the mass using an electronic balance
Measure the volume with a eureka can by collecting the displaced water and using a measuring cylinder
Calculate Density (mass / volume)
Density PAG - how can the density of a liquid be found?
Measure the volume with a measuring cylinder
Place a beaker on an electronic balance and record the mass.
Add the liquid to the beaker and record the new mass
Calculate the mass of the liquid (final mass - initial mass)
Calculate Density (mass / volume)
Resistance PAG 1 - Describe a method to find the resistance of a wire
Set up a power pack connected to an ammeter in series and to a resistance wire and a voltmeter in parallel to the wire.
Set the crocodile clips so they are 10 cm apart.
Measure the current with an ammeter and the potential difference with a voltmeter.
Calculate the resistance using R = V/I
Repeat for other lengths
Resistance PAG 1 - State the variables and whether they are continuous, discrete and catergoric
Independent - length of wire - continuous
Dependent - current and voltage to calculate resistance -continuous
Controls - Temperature of wire - continuous, type of wire catergoric
Resistance PAG 1 - Describe the expected results
As length of wire increases so does the resistance. Length and resistance will be directly proportional to each other. The graph would be a straight line through the origin.
Resistance PAG 1 - what would have caused the main error in the experiment and how could it be reduced.
Wire heating up - use a small current and turn the power off after each reading so the wire cools down.
Measuring the length of the wire due to the thickness of the crocodile clips - use thiner crocodile clips.
Resistance PAG 1 - Describe a suitable risk assessment
Wire will get hot - this could burn you - use a small current and turn the power off in-between readings
Resistance PAG 2 - What happens to total resistance when resistors are added in series?
Total resistance will increase as the current (electrons) will need to pass through all resistors in series
Resistance PAG 2 - What happens to total resistance when resistors are added in parallel?
Total resistance will decrease as the current (electrons) have more paths to take back to the battery.
I-V graphs PAG - Describe the circuit needed to find the I-V characteristics of a component.
A power pack in series to an ammeter, a variable resistor and the component in question. A voltmeter in parallel to the component.
I-V graphs PAG - Describe a method find the I-V characteristics of a component.
Set up the circuit and use the ammeter to measure the current and a voltmeter to measure the voltage.
change the resistance in the circuit using the variable resistor and measure the current and voltage again.
Repeat 6 times to collect enough data to draw a graph.
I-V graphs PAG - Describe the graph for a resistor
A straight line through the origin - current and voltage are directly proportional and it obeys ohms law
I-V graphs PAG - Explain the graph for a resistor
As potential difference increases there is a bigger push on the electrons so they move around the circuit more quickly. The flow of electrons is the current so current increases proportionally.
I-V graphs PAG - Define ohms law
Current is directly proportional to potential difference as long as temperature remains constant
I-V graphs PAG - Describe the graph for a bulb
As voltage increases so does the current but the current levels off and the graphs curves.
I-V graphs PAG - Does a bulb obey ohms law?
No the graph curves and levels off so isnt directly proportional
I-V graphs PAG - Explain the graph for a bulb
The bulb heats up which causes the atoms to vibrate faster and take up more space. This makes is harder for the electrons to travel down the wire. This causes the resistance to increase.
I-V graphs PAG - Describe the graph for a diode
No current in the negative direction.
In the positive direction current increases quickly
I-V graphs PAG - Does a diode obey ohms law?
No the graph isn’t a straight line through the origin.
I-V graphs PAG - Explain the graph for a diode
In the negative direction a diode has a massive resistance which stops any current from flowing.
In the positive direction a diode has a low resistance so a large current can flow.
SHC PAG - State the units of SHC
J/kgoC
SHC PAG - Define SHC
The amount of energy neeed to change the temperature of a 1 kg substance by one degree Celsius
SHC PAG - What measurements are needed?
c = Energy / (mass x temperature change)
so need to measure:
Energy provided
mass
temperature change
SHC PAG - How can the energy provided be found?
Method 1 - Use a joulemeter to measure the energy provided directly
Mathod 2 - Use an ammeter to measure current, voltmeter to measure voltage and stopwatch to measure time
Power = VI
Energy = power x time
SHC PAG - What are the main causes of energy and how can they be reduced?
Heat losses to the surroundings, reduced by insualting the material that is being heated.
SHC PAG - Describe a method to find the SHC of a material
Measure the mass of the material
Measure the initial temperature of the material
Place an electrical heater in the material.
Time for 10 minutes and then find the final temperature
Calcualate the temperature increase
Calcaute the SHC = Energy / (mass x temperature change)
