Wave and image questions in SPM Physics test whether you can read a labelled diagram before you calculate anything. This hub gathers four lessons and one practice set that train that habit.
It sits inside SPM Physics waves, so the formulas themselves are taught there. Here the focus is the reading step that comes first.
What do these lessons cover?
Each lesson handles one diagram skill that students often treat as obvious and then get wrong.
- Amplitude versus frequency on a wave graph: which feature of the picture changed, and which quantity that means.
- A time axis instead of a distance axis: how to get period, frequency and wavelength from the right graph.
- Lens images and the sign convention: checking a ray diagram against the lens formula.
- Explaining a diffraction comparison: writing what the diagram shows in full sentences.
How do the skills connect?
The first two lessons are about axes, so they belong together. A crowded wave can mean a short wavelength or a short period, and only the axis label decides which.
The lens lesson adds a second kind of label: the sign of a distance. The diffraction lesson then asks you to put a diagram into words, which uses the reading skills from all three.
One example of a hidden second question
A graph shows a wave with peaks 4 cm above and troughs 4 cm below the axis, and the horizontal axis is marked in seconds. The question asks for the wavelength.
The graph cannot give a wavelength directly, because a time axis gives the period. You first read the period, then combine it with the given wave speed using v = fλ. Seeing this before any arithmetic is the skill these lessons practise.
Where should you start?
If graph questions feel shaky, begin with the amplitude and frequency lesson, then the time-axis lesson. If graphs are fine but the lens formula gives confusing signs, go straight to the lens lesson.
When you finish, try the integrated practice set. Wrong answers there point you back to the lesson that fixes them.
To keep track of which diagram errors repeat, the mistake log and paper-error review helps you group them. For teacher support with your own questions, see online one-to-one Physics tuition.