Waves, the spectrum and their uses
All waves transfer energy without transferring matter. One equation and one classification cover most of the topic.
Lesson overview
What you'll learn in this lesson
Apply the laws of motion and wave behaviour to explain and calculate.
Key learning points
- • Describing waves
- • The electromagnetic spectrum
- • Behaviour and hazards
This lesson at a glance
- 30 minutes
- 19 parts to scroll through
- 4 quick checks
- Marked quiz at the end
- Gentle pace: short sittings with pauses
Words to know
Scroll down — the lesson carries on below
Watch & discover
Part 1 of 19
Visual introductionPicture this
Waves, the spectrum and their uses
All waves transfer energy without transferring matter. One equation and one classification cover most of the topic.
In a nutshell
Apply the laws of motion and wave behaviour to explain and calculate.
Learning cycle
Part 2 of 19
Learning cycle 1 of 2
Part 1 · Describing waves
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 3 of 19
Learn
Describing waves
Amplitude is the maximum displacement from rest, wavelength the distance between corresponding points and frequency the number of waves per second in hertz. The wave equation v = fλ links them. In transverse waves the oscillation is perpendicular to the direction of travel; in longitudinal waves, such as sound, it is parallel.
Reset break
Part 4 of 19
Pause
That's sitting 1 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Explore the idea
Part 5 of 19
Learn
The electromagnetic spectrum
Radio, microwave, infrared, visible, ultraviolet, X-ray and gamma, in order of increasing frequency and decreasing wavelength. All travel at the same speed in a vacuum. Uses follow properties: microwaves for communication and heating, infrared for thermal imaging, X-rays for medical imaging, gamma for sterilisation.
Quick check
Part 6 of 19
Quick check
Part 7 of 19
Reset break
Part 8 of 19
Pause
That's sitting 2 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Learning cycle
Part 9 of 19
Learning cycle 2 of 2
Part 2 · Behaviour and hazards
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 10 of 19
Learn
Behaviour and hazards
Waves reflect, refract when they change speed entering a new medium, and can be absorbed or transmitted. Higher-frequency radiation carries more energy, so ultraviolet can damage skin cells and X-rays and gamma rays can cause mutations, which is why exposure is controlled and shielding is used.
Quick check
Part 11 of 19
Reset break
Part 12 of 19
Pause
That's sitting 3 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Quick check
Part 13 of 19
Explore the idea
Part 14 of 19
Worked example
Worked answer: a wave has frequency 50 Hz and wavelength 6 m. Find its speed (3 marks)
The wave equation is v = fλ (1). Substituting: v = 50 × 6 (1) = 300 m/s (1). Rearranging, a wave of the same speed with double the frequency would have half the wavelength, since speed is fixed by the medium the wave travels through.
Challenge round
Part 15 of 19
Game · Sort it
Which of these are true?
Drag each card into the right column. Tap a card first if dragging is fiddly.
True
Not true
Reset break
Part 16 of 19
Pause
That's sitting 4 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Challenge round
Part 17 of 19
Game · Recall cards
The wave equation is
Card 1 of 4
Mastery quiz
Part 18 of 19
Marked quiz
End of lesson quiz: Waves, the spectrum and their uses
4 questions, marked with the reasoning shown. No timer.
1. The wave equation is
2. Sound is a
3. Which has the highest frequency?
4. Refraction happens because a wave
Lesson round-up
Part 19 of 19
Lesson round-up
Ready when you are
Quiz score
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Luna: 0 out of 4 on the practice checks. Only if you feel up to it — one more?
Ask LunaPart 1 of 19 · Watch & discover