Exploring Standing Waves: Melde's Experiment & Wave Phases

[Badrakhandama]

I am stuck on a question about standing waves:

'The diagram below show's Melde's experiment and demonstartion of a stationary wave on a string'

The string has 3 full wavelengths shown, and 3 points are marked:

Point A is on an antinode, Point B is on the same antinode, but very fractionally to the right, and point C is on an antinode out of phase (see the attachment for a similar diagram) - A is in red, B is in black, C is in blue

The first question is easy:
"State whether the following paris of points on the string are in phase, in antiphase, or neither in phase nor antiphase

A and B - I put that they are both in phase
A and C - I put that they are in antiphase

The next question (the tough nut):
"Describe briefly how you could check this experimentally"

I have no idea!

Any form of help/guidance will be much appreciated

Homework Equations

The Attempt at a Solution

 

[jbsteele]

One way to check this experimentally is to use a device such as an oscilloscope to measure the relative phase of the two points. Using the oscilloscope, you can measure the voltage of each point and determine whether the two points are in phase or out of phase. If the two points are in antiphase, then the voltage at one point will be the exact opposite of the voltage at the other point. Alternatively, you could also use a tuning fork to measure the frequency of the wave at each point, and compare the two frequencies to determine if the two points are in phase or out of phase.