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: Waves
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Study Hack Lab
RP 8 · Physics
Waves
Write-up template
Name
Date
Course
GCSE Physics
Board and specification
AQA GCSE Physics (8463), 4.6.1.2AQA GCSE Combined Science: Trilogy (8464), 6.6.1.2Apparatus and techniques: AT 4
Class and teacher
Aim
Measure the frequency, wavelength and speed of water waves in a ripple tank and of waves on a stretched string, and decide which apparatus and methods measure them best.
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
Wave speed = frequency × wavelength. The frequency is how many waves pass a point each second; the wavelength is the distance from one crest to the next. The speed is set by what the wave travels through (the depth of the water, the tension in the string), so a higher frequency means a shorter wavelength.
v = f λ
Variables
Independent (you change)
Dependent (you measure)
Control (you keep the same)
Prediction
In the ripple tank, the motor is turned up so the frequency doubles. What happens to the waves?
The lamp shines down through the waves onto the card below. Is the pattern on the card the same size as the real waves?
On the string, you turn the frequency up until there are more loops. What happens to the wavelength?
Risk assessment
Hazard
Harm it could cause
Control
2 Apparatus
Ripple tank with a glass floor Holds the water the waves travel through.
Wooden bar on a motor, with its power unit Makes straight waves at a steady frequency.
Lamp on a stand above the tank Shines through the waves to make a pattern of bright lines.
Large sheet of white card The screen under the tank that the pattern falls on.
Two metre rules (resolution 1 mm) Measure distances on the card and along the string.
10 cm plastic ruler A scale in the tank to find how much the pattern is magnified.
Phone with a camera Photographs the pattern, or films it in slow motion.
Tally counter and stopwatch Counts the waves passing a mark in 10 s.
Signal generator and vibration generator (resolution 0.1 Hz) Vibrates the string at a frequency you set and read.
String, pulley and bench clamp The string the waves travel along.
100 g hanger and one 100 g slotted mass Keeps the tension in the string the same.
Safety goggles Protect your eyes near the vibrating string.
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.
The scale in the tank · Magnification = length of the shadow ÷ real length.
Object
Length in cm
Ruler in the tank
Its shadow on the card
Distance across 8 waves on the card · Wavelength on the card = distance ÷ 8.
Trial
Distance across the waves in cm
Wavelength on the card in cm
1
2
3
Mean
Waves passing the mark in 10 s · Frequency = number of waves ÷ 10 s.
Trial
Number of waves in 10 s
Frequency in Hz
1
2
3
Mean
Waves on the string · Each loop is half a wavelength: wavelength = 2 × length ÷ number of loops.
Number of loops
Frequency in Hz
Length across the loops in cm
Wavelength in m
Wave speed in m/s
2
3
4
5
6
Anomalies
Ring any anomalous result. Say what probably went wrong and whether you repeated it.
5 Graph
Wavelength against frequency · Choose your axes: the independent variable goes on the x-axis. Label each axis with the quantity and unit.
6 Analysis
Wavelength on the card
wavelength = distance across the waves ÷ number of waves
Answer
Wavelength of the water waves
real length = length on the card ÷ magnification
Answer
Frequency of the water waves
frequency = number of waves ÷ time
Answer
Speed of the water waves
wave speed = frequency × wavelength (v = f λ)
Answer
Wavelength on the string (3 loops)
one loop = half a wavelength
Answer
Speed of the waves on the string
wave speed = frequency × wavelength (v = f λ)
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 pattern on the card is magnified by the spreading light from the lamp
Counting fast-moving waves by eye
Measuring across one wave instead of many
Judging the middle of moving, blurred lines
Water deeper at one end of the tank
Stopping as soon as the loops appear on the string
Judging where the blurred nodes on the string are
Starting and stopping the count a moment early or late
Improvement
How could you improve the method? Say why it would help.
8 Make safe and clear up
Turn the signal generator to zero and switch it off, then lift off the masses and unhook the string
Switch off the motor and the lamp
Drain the ripple tank into the sink and mop up any spills straight away
Put the metre rules, card and phone away, and switch the room lights back on