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