Summary
Highlights
Waves transfer energy, not matter, from one point to another. Examples include light waves from a phone screen and sound waves from speakers, where only energy is moved, often conveying meaningful information to our brains.
Waves oscillate, as shown in a displacement-distance graph. Displacement is the vertical distance from the equilibrium point, while distance is how far the wave has traveled horizontally. The maximum displacement is the amplitude, and one complete oscillation's length is the wavelength, spanning from crest to crest or trough to trough.
A displacement-time graph shows the time taken for one complete oscillation, known as the time period. The frequency, measured in Hertz, is the number of complete oscillations per second and can be calculated as 1 divided by the time period (f = 1/T).
Wave speed is calculated by multiplying the wavelength by the frequency (v = λf). For example, a sound wave with a frequency of 400 Hz and a wavelength of 70 cm (0.7 m) would have a wave speed of 280 meters per second.
In transverse waves, oscillations are perpendicular to the direction of energy transfer. Common examples include all electromagnetic waves (light, radio), water ripples, and waves on a guitar string.
Longitudinal waves have oscillations parallel to the direction of energy transfer, creating regions of compression and rarefaction. Sound waves and seismic P-waves are examples of longitudinal waves.