Wave properties
Waves transfer energy without transferring matter. Transverse waves oscillate at right angles to the direction of travel (light, water). Longitudinal waves oscillate parallel (sound) and have compressions and rarefactions.
Wave speed v = fλ. Frequency is waves per second; wavelength is the distance between the same point on two waves. Amplitude is the maximum displacement from the rest position.
EM spectrum
Radio, microwave, infrared, visible, ultraviolet, X-ray, gamma. All travel at 3 × 10⁸ m/s in a vacuum. Higher frequency means higher energy and usually more danger to cells. Uses: radio communications, cooking, thermal imaging, vision, sterilising, medical imaging, cancer treatment.
Sound and required practicals
Sound needs a medium. Measure wave speed in a ripple tank or with a string and a signal generator. Reflection: angle of incidence equals angle of reflection. Refraction occurs when waves change speed at a boundary.
Download Waves slides (PowerPoint)
Taught with support from Joseph Danso, Science Lecturer in London. Book a session.