What are the properties of waves, how do we use the wave equation, and what is the electromagnetic spectrum?
Transverse and longitudinal waves, the wave terms amplitude, wavelength, frequency and period, the wave equation, the order of the electromagnetic spectrum with its shared properties, and the uses and dangers of the EM waves.
A focused CCEA GCSE Single Award Science answer on waves, covering transverse and longitudinal waves, the wave terms, the wave equation, the order of the electromagnetic spectrum with its shared properties, and the uses and dangers of the EM waves.
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What this dot point is asking
CCEA wants you to distinguish transverse and longitudinal waves, define the wave terms, use the wave equation, give the order of the electromagnetic spectrum with its shared properties, and state the uses and dangers of the EM waves.
Transverse and longitudinal waves
In both, the wave transfers energy, but the medium only vibrates about a fixed position; it is not carried along.
Wave terms and the wave equation
The electromagnetic spectrum
All EM waves are transverse, travel through a vacuum at the same speed ( m/s), and transfer energy. Uses include radio for broadcasting, microwaves for cooking and communications, infrared for heaters and remote controls, visible light for seeing, ultraviolet for sterilising, X-rays for imaging bones, and gamma rays for sterilising equipment and treating cancer. The higher-energy waves (ultraviolet, X-rays, gamma) are ionising and can damage cells.
Examples in context
Example 1. Why we cannot hear in space but can still see. Sound is a longitudinal wave that needs particles to pass on the vibrations, so it cannot travel through the vacuum of space. Light is an electromagnetic wave that needs no medium, so it crosses the vacuum easily, which is why we see distant stars but hear nothing. This contrasts the two wave types directly.
Example 2. Matching an EM wave to its use through its energy. The uses follow from the properties: gamma rays carry so much energy that they kill cells and microbes, so they sterilise equipment and treat cancer; radio waves carry little energy and travel far, so they suit broadcasting. Choosing the right wave for a job, and explaining the choice using frequency and energy, is exactly what CCEA tests in EM-spectrum questions.
Try this
Q1. Give the wave equation. [1 mark]
- Cue. (wave speed equals frequency times wavelength).
Q2. Which type of wave is sound, transverse or longitudinal? [1 mark]
- Cue. Longitudinal.
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA SAS 20203 marksA wave has a frequency of 50 Hz and a wavelength of 4 m. Calculate its speed.Show worked answer →
Three marks for the formula, the substitution and the answer.
Use the wave equation: wave speed equals frequency times wavelength, v equals f times lambda.
v equals 50 times 4, which equals 200.
So the wave speed is 200 m/s. Markers reward the correct formula, the substitution and the unit metres per second.
CCEA SAS 20194 marksState the order of the electromagnetic spectrum from lowest to highest frequency, and give one use of microwaves and one use of X-rays.Show worked answer →
Four marks for the order and the two uses.
In order of increasing frequency: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.
A use of microwaves: cooking food, or mobile phone and satellite communication.
A use of X-rays: imaging bones, or airport security scanning.
Markers reward the correct order (radio lowest, gamma highest) and one valid use for each named wave.
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Sources & how we know this
- CCEA GCSE Science: Single Award specification — CCEA (2017)