A wave transfers energy from one place to another without transferring matter. Water waves bob a floating duck up and down, but the duck does not travel with the wave. Waves are described by their amplitude (the height from the middle to a peak), their wavelength (the distance from one peak to the next) and their frequency (how many waves pass a point each second, in hertz, Hz).
In a transverse wave the vibrations are at right angles to the direction the wave travels, like a rope shaken up and down, water waves and light. In a longitudinal wave the vibrations are along the direction of travel, making compressions and rarefactions, like sound and a slinky pushed back and forth. A bigger amplitude carries more energy.
Worked example
Five waves pass a buoy every second. What is the frequency?
- Frequency = number of waves per second.
- 5 waves each second.
Answer:The frequency is 5 Hz.
Key words
- amplitude
- height of a wave from the middle to a peak
- wavelength
- distance from one peak to the next
- frequency
- waves per second, in hertz (Hz)
- transverse
- vibrations at right angles to travel
- longitudinal
- vibrations along the direction of travel
New questions every time.
NGSS-referenced: MS-PS4-1