Physics Question help, waveforms....

AshleyC

AshleyC

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Im trying to work out what frequency this wave is and im simply unsure what constitutes a single wave. Would i measure from A to B or would i do C to D




As far as frequency goes do i just treat this as a long line of small waves or a slower frequency wider wave with all the little ones making up one big one! Also with regards to the Amplitude, do i measure from the 0 line to the highest peak or from the middle of one of the little waves to the peak?
 
A single wave is one complete cycle: start at a midpoint, go up to a peak, down to a trough and back to the midpoint.

Amplitude is from the top of a peak to the midpoint, or bottom of a trough to a midpoint :)
 
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OK thanks, so in my example there, one wave is a to b?
 
Well, from 1 to about 245 on the seconds line.
 
What you have there is a higher frequency sinusoidal wave combined with a lower frequency square wave, so you need to know whether you are talking about the combined waveform (this is the most likely question) or the constituent waveforms.

As Kendo says, to calculate the frequency you need to measure the wavelength - start at a point where it crosses the X-axis going up then measure to the next time it crosses the X-axis going up (there'll be a going down point in the middle of those two). Frequency is then 1/wavelength.

Maximum amplitude of the combined waveform is from the X-axis to the highest point.
 
AshleyC said:
OK thanks, so in my example there, one wave is a to b?
Click to expand...

Edit: You have several waves in the diagram, I just realised that Kendo was looking at the other one.
You have one overarching square wave with a period of around 245 seconds but you also have a smaller wave on top of it with a period of around 25 seconds.


One cycle is from a peak to the next peak. Really it's from any point to where it then repeats itself to make up the whole wave but going peak to peak or trough to trough is normally the easiest to measure.

Your section A contains 5 cycles of the smaller wave.
 
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This is just a homework question im working on and just trying to get my head round it :) The question is to work out the frequency of the highest amplitude wave, so this would be the bigger square wave, A to B then. Up till now ive just been doing reasonably simple sine waves, this is first one with multiple sizes so its throwing me a little :)

thanks for the help :)
 
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