Stationary waves

Question 1

How are stationary waves formed

Answer 1

When two waves travel in opposite directions, the two waves have the same amplitude and frequency
Normally a wave is reflected off a fixed end
The two waves superpose
They create nodes and antinodes

Question 2

What are nodes ?

Answer 2

A point of 0 amplitude

Question 3

What are antinodes?

Answer 3

A point of maximum amplitude

Question 4

What is the phase difference in stationary waves ?

Answer 4

Between adjacent nodes all the particles are in phase
Particles on different sides of a node are in antiphase ( 180 degrees out of phase )

Question 5

What does in phase mean ?

Answer 5

This means that all the particles are moving up

Question 6

Stationary waves vs progressive waves

Answer 6

Progressive waves transfer energy in the direction of travel
Stationary waves no energy is transferred
The amplitude is constant across all points in a progressive
The amplitude varies along a stationary wave

Question 7

Wavelength in stationary waves

Answer 7

Distance between adjacent nodes (or antinodes) is lamda/ 2

Question 8

What is a harmonic ?

Answer 8

Only specific frequencies create stationary waves

Question 9

What are the different harmonics ?

Answer 9

Fundamental (1)is at 30 hz L=lamda/2
2 is at 60hz and L= lamda
3 is at 90hz and L= 3lamda / 2