Exam 16: Superposition and Standing Waves

A string fixed at both ends that is vibrating in its eighth harmonic will have 8 antinodes and 9 nodes.

A guitar string is fixed at both ends.If you tighten it to increase its tension,the frequencies of its normal modes will increase but its wavelengths will not be affected.

An open pipe,0.95 m long,vibrates in the second overtone with a frequency of 561 Hz.In this situation,the distance from the center of the pipe to the nearest antinode,in cm,is closest to:

You press two flat pieces of glass together so that a very thin layer of air is trapped between them.Incoming light can reflect from the boundary between the top glass plate and the air,and also from the boundary between the air and the bottom plate;the two reflected waves can then interfere with each other.What is the smallest spacing between the plates that will produce a strong reflection when red light of 680 nm wavelength shines perpendicularly on them?

A string 2.0 m long and fixed at both ends is vibrating in its fourth harmonic in a room at 20C.The wavelength of the sound it produces is 1.0 m.