Idea 3of 9Builds onHow tall
How long
Shake the rope more often. What changes?
Today you'll discover
- what shaking more often changes, and what it leaves alone
- the spacing of a pattern, crest to crest
- the name for that spacing
Think firstA rope shaken at one rate, then twice as often
You shake the rope twice as often, no harder. What changes in the picture?
Decide first, then press Next. Watch the spacing change while the height stays put.
A wave on a rope. After a prediction, the rope is redrawn shaken twice as often, with crests half as far apart at the same height, then a bracket is drawn from one crest to the next and named. The last step compares two ropes shaken at different rates and asks about the spacing.
See the whole ideathe big idea and the key word, in one place
The big idea
Wavelength is the spacing: one crest to the next, written λ.
Compare themHarder: taller, same spacing. More often: closer, same height. Two dials, and neither one touches the speed.
Key word
- wavelength
- the distance from one crest to the next, one full repeat of the pattern; symbol λ, in metres
About this modelThe pattern travels; the particle only bobs. One square of the drawing is 0.5 m.
The pattern travels; the particle only bobs. One square of the drawing is 0.5 m.
Ready to use it?
- Read the wavelength off a drawn wave, crest to crest or trough to trough.