A blank nine-step write-up with the correct table headings. Print it for a real lesson and fill it in by hand. See the specimen lab book
Blank write-up: I–V characteristics
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Study Hack Lab
RP 4 · Physics
I–V characteristics
Write-up template
Name
Date
Course
GCSE Physics
Board and specification
AQA GCSE Physics (8463), 4.2.1.4AQA GCSE Combined Science: Trilogy (8464), 6.2.1.4Apparatus and techniques: AT 6, AT 7
Class and teacher
Aim
Measure how the current through a resistor, a filament lamp and a diode depends on the potential difference across it, in both directions, and plot their I–V characteristics.
Contents
Plan and risk assessment
Apparatus
Method
Results
Graph
Analysis
Conclusion and evaluation
Make safe and clear up
A blank write-up for use in a real lesson. The headings follow the AQA required practical; the readings are yours to take. Layout v1, practical v2. Original material; not affiliated with AQA, which has not reviewed it.
1 Plan and risk assessment
Resistance = potential difference ÷ current, at any point on an I–V graph. A resistor at constant temperature gives a straight line through the origin. A filament lamp’s resistance rises as it heats, so its graph flattens off. A diode lets current flow one way only.
V = I R
Variables
Independent (you change)
Dependent (you measure)
Control (you keep the same)
Prediction
What will a graph of current against potential difference look like for the resistor?
And for the filament lamp?
And for the diode?
Risk assessment
Hazard
Harm it could cause
Control
2 Apparatus
Low-voltage power pack (0–12 V DC) Drives the current; its dial sets the pd.
Digital ammeter (multimeter) (resolution 0.1 mA or 0.01 A) Measures the current through the component, in series: 200 mA range (0.1 mA) or 10 A range (0.01 A).
Digital voltmeter (multimeter on the 20 V range) (resolution 0.01 V) Measures the potential difference across the component, in parallel.
Component holder with two 4 mm sockets Holds each component in turn.
100 Ω resistor (1 W) The first component: an ohmic conductor at constant temperature.
Filament lamp, 12 V 24 W The second component.
Silicon diode with protective resistor P (10 Ω) The third component; P limits its current.
10 Ω rheostat (5 A) Optional: varies the lamp’s pd with the pack on 12 V.
Six 4 mm leads Connect the circuit.
3 Method
Write numbered steps someone else could follow. Say what you measure, with which instrument, and how you keep it a fair test.
4 Results
The table is drawn before you measure. Record each reading to the resolution of the instrument, then work out the mean of your repeats, leaving out any anomaly.
Resistor (100 Ω) · Reversed readings are negative: write the minus sign.
Power pack
Potential difference in V
Current in mA
2 V
4 V
6 V
8 V
4 V, reversed
8 V, reversed
Filament lamp (12 V 24 W)
Power pack
Potential difference in V
Current in A
1 V
2 V
4 V
6 V
9 V
12 V
2 V, reversed
6 V, reversed
12 V, reversed
Diode (with protective resistor P)
Power pack
Potential difference in V
Current in mA
0.4 V
0.6 V
0.8 V
1 V
1.5 V
2.5 V
1 V, reversed
2.5 V, reversed
Anomalies
Ring any anomalous result. Say what probably went wrong and whether you repeated it.
5 Graph
The resistor: current against potential difference · Choose your axes: the independent variable goes on the x-axis. Label each axis with the quantity and unit.The filament lamp · Choose your axes: the independent variable goes on the x-axis. Label each axis with the quantity and unit.The diode · Choose your axes: the independent variable goes on the x-axis. Label each axis with the quantity and unit.
6 Analysis
Resistance
Answer
The lamp at its lowest pd
resistance = potential difference ÷ current (V = I R)
Answer
The lamp at its highest pd
resistance = potential difference ÷ current (V = I R)
Answer
Inside the filament
Answer
7 Conclusion and evaluation
Conclusion
Conclusion: what do your results show? Use your own numbers.
Sources of error
For each, say whether it is systematic or random, and how it affected your results.
The ammeter’s resolution at small currents
Reading the lamp before the filament had settled
The meters’ calibration
A rheostat in series cannot take the lamp below about 3 V
Improvement
How could you improve the method? Say why it would help.
8 Make safe and clear up
Turn the power pack down to 0 V and switch it off
Let the lamp cool before you touch it or take it out