The Electromagnetic Spectrum
The electromagnetic spectrum encompasses all types of electromagnetic radiation, from low-frequency radio waves to high-frequency gamma rays, each with distinct properties and applications.
What You Need to Know
Key Concept Diagram
All electromagnetic waves travel at the speed of light (3 × 10⁸ m/s) in a vacuum and do not require a medium to travel
The spectrum from lowest to highest frequency: radio → microwave → infrared → visible light → ultraviolet → X-ray → gamma ray
As frequency increases, wavelength decreases and energy increases (E = hf, where h is Planck's constant)
Each region has practical applications: radio (communication), microwave (cooking, radar), infrared (remote controls, thermal imaging), X-ray (medical imaging), UV (sterilisation)
Key Vocabulary
Electromagnetic radiation
Energy transmitted through oscillating electric and magnetic fields that can travel through a vacuum at the speed of light
Frequency
The number of wave cycles passing a point per second, measured in hertz (Hz); higher frequency means higher energy
Wavelength
The distance between successive crests (or troughs) of a wave; inversely related to frequency
Ionising radiation
Electromagnetic radiation with enough energy to remove electrons from atoms (ultraviolet, X-rays, gamma rays), which can damage biological tissue
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
Which region of the electromagnetic spectrum has the highest frequency and most energy?
Question 2
Ultraviolet radiation from the Sun can cause skin cancer. Why is UV radiation potentially harmful to cells?
Question 3
Which property do ALL types of electromagnetic radiation share?
Key Concepts Summary
- ●All electromagnetic waves travel at the speed of light (3 × 10⁸ m/s) in a vacuum and do not require a medium to travel
- ●The spectrum from lowest to highest frequency: radio → microwave → infrared → visible light → ultraviolet → X-ray → gamma ray
- ●As frequency increases, wavelength decreases and energy increases (E = hf, where h is Planck's constant)
- ●Each region has practical applications: radio (communication), microwave (cooking, radar), infrared (remote controls, thermal imaging), X-ray (medical imaging), UV (sterilisation)