4PH1

Waves & The Electromagnetic Spectrum

Waves · 1 question type

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 14% of your exam marks.

stable

High

Stable14%

Wave equation (v = fλ), transverse vs longitudinal and EM spectrum properties tested consistently.

A wavefront is a line joining all the points of a wave that are currently in step (for example, every point at the top of its peak)
Wavefronts are usually drawn from above, like contour lines on a map:
- Closely spaced indicate a short
- Widely spaced wavefronts indicate a long wavelength
A ray is an arrow drawn perpendicular to the wavefronts, showing the direction of travel of the wave

The (A) of a wave is the distance from the undisturbed (rest) position to either a peak or a trough, not the full peak-to-trough height
Amplitude is measured in metres (m)
The amplitude of a wave is a measure of how much energy it carries; a wave with twice the amplitude transfers roughly four times the energy in the same time

The wavelength (λ) of a wave is the distance from one point on the wave to the same point on the next wave:
- in a transverse wave, peak-to-peak (or trough-to-trough)
- in a longitudinal wave, centre of one compression to centre of the next
Wavelength is measured in metres (m) and uses the Greek letter lambda (λ)

The (f) of a wave is the number of complete waves that pass a fixed point each second
Frequency is measured in hertz (Hz); 1 Hz = one per second
A wave with a higher frequency carries more energy per second (for the same amplitude and medium)

The (T) of a wave is the time taken for one complete wave to pass a fixed point
Period is measured in seconds (s)
Frequency and period are reciprocals of one another:

f = 1 / T and equivalently T = 1 / f