Which of the following is a standing wave?
Ocean waves hitting a pier every ten seconds
The sound made by an electric fan
A bus rumbling over a metal bridge
Light with a wavelength of exactly
A vibrating violin string
A guitar string has a length of . If the string is vibrating with a wavelength of , what harmonic is it vibrating at?
First
Fifth
Fourth
Second
Third
. If the string is vibrating with a wavelength of 
, what harmonic is it vibrating at?