“Another commonly encountered wave-like phenomenon is ‘electromagnetic radiation’, exemplified in the radio waves that bring signals to our radios and televisions and in light. These waves have different frequencies and wavelengths: for example, typical FM radio signals have a wavelength of 3 m, whereas the wavelength of light depends on its colour, being about 4 × 10−8 m for blue light and 7 × 10−8 m for red light; other colours have wavelengths between these values.”