Electromagnetic waves are unique waves formed by oscillating electric and magnetic fields perpendicular to each other. Unlike mechanical waves, they do not require a medium to travel and can move through a vacuum at the speed of light. From long radio waves used in communications to energetic gamma rays used in medicine, electromagnetic waves form a continuous spectrum that plays an essential role in modern daily life and technology.
See the continuous arrangement of electromagnetic waves according to frequency and wavelength, alongside their key real-world applications.
The spectrum is continuous — there is no specific boundary separating two adjacent types of waves.
Electromagnetic waves are transverse waves produced by oscillating electric and magnetic fields at right angles to each other and to the direction of wave travel.
Because they do not need physical particles to vibrate, electromagnetic waves propagate through the vacuum of space at a constant maximum speed of \(3.00 \times 10^8\ \mathrm{m\,s^{-1}}\).
Electromagnetic waves exhibit reflection, refraction, diffraction and interference under suitable conditions.
The energy carried by an electromagnetic wave is directly proportional to its frequency. Gamma rays and X-rays carry large amounts of energy and can be hazardous to living tissues if not handled properly.
Wave speed in a vacuum
where \(c = 3.00 \times 10^8\ \mathrm{m\,s^{-1}}\), \(f\) is frequency and \(\lambda\) is wavelength.
Answer in your mind, then press “Check Answer”.
An electromagnetic spectrum is arranged in order of increasing frequency: Gamma ray, X-ray, \(B\), Visible light, Infrared ray, \(C\), Radio wave. Identify wave \(B\) and wave \(C\).
State two characteristics shared by all electromagnetic waves.
In air, blue light has a wavelength of \(420\ \mathrm{nm}\) and travels at \(3.00 \times 10^8\ \mathrm{m\,s^{-1}}\). Its speed drops to \(2.25 \times 10^8\ \mathrm{m\,s^{-1}}\) when entering a liquid. What is the wavelength of this blue light in the liquid?
Electromagnetic waves travel at the speed of \(3.00 \times 10^8\ \mathrm{m\,s^{-1}}\) in all media.
Electromagnetic waves travel at \(3.00 \times 10^8\ \mathrm{m\,s^{-1}}\) in a vacuum (and approximately in air). When they enter physical media like glass, water or oil, their speed is lower.
There are clear, distinct boundary lines separating adjacent types of electromagnetic waves.
The electromagnetic spectrum is a continuous spectrum, meaning there is no specific boundary separating two adjacent types of waves.
Objective: Test your understanding of the electromagnetic spectrum, wave speed and applications.
1 Which of the following electromagnetic waves has the highest frequency and carries the largest amount of energy?
2 What happens to an electromagnetic wave when it passes from a vacuum into a denser medium such as glass?
3 For all electromagnetic waves propagating through a vacuum, the formula \(v = f\lambda\) is written as \(c = f\lambda\), where the speed of propagation \(c\) is equal to m s⁻¹.
4 An electromagnetic wave consists of an electric field and a magnetic field that oscillate to one another.
Match each type of electromagnetic wave to its correct daily life application. If using a phone, tap the answer first, then tap the matching box.
There is something wrong with this question.
