Calculate phase between sine waves given the time difference

In summary: This means that any calculations you do with it should also contain just one significant figure. Therefore, the final answer of -0.044 is correct to 3 significant figures, meaning the difference in seconds is indeed due to rounding error. In summary, the phase difference between sine waves can be found using the equation time difference * 2*Pi*f = phase difference in radians, and in this case, the difference in seconds is due to rounding error.
  • #1
exidez
44
0

Homework Statement



How do i find the phase between sine waves knowing the time difference between each?
http://users.bigpond.net.au/exidez/sinewave.jpg

Equation for the main function is 3cos(30t - Pi/2)
The smaller sine wave is of the same frequency when is settles in a steady state.


Homework Equations



i thought it was
time difference * 2*Pi*f = phase difference in radians

The Attempt at a Solution


30 = 2*Pi * f

-.05*30 = 1.5 radians
-1.5*360/(2Pi) = -85.94 degrees

MATLAB give the phase difference as -76.3995 degrees
this is equivalent to -0.0444474274 difference in seconds

Is this just due to rounding error??
 
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  • #2
i think i just answered my own question... 2.57 seconds for the larger sine wave still give an amplitude of 3.. In this case the time difference is -0.04.

it definitely is due to rounding
 
  • #3
exidez said:

Homework Statement



How do i find the phase between sine waves knowing the time difference between each?
<image not shown>

Equation for the main function is 3cos(30t - Pi/2)
The smaller sine wave is of the same frequency when is settles in a steady state.

Homework Equations



i thought it was
time difference * 2*Pi*f = phase difference in radians

The Attempt at a Solution


30 = 2*Pi * f

-.05*30 = 1.5 radians
-1.5*360/(2Pi) = -85.94 degrees

MATLAB give the phase difference as -76.3995 degrees
this is equivalent to -0.0444474274 difference in seconds

Is this just due to rounding error??

You did it right, but note that the 0.05s time difference contains just one significant figure.
 

1. How do you calculate the phase between two sine waves given a time difference?

To calculate the phase between two sine waves, you first need to determine the period of the waves. This can be done by finding the time it takes for the wave to complete one full cycle. Once you have the period, you can use the formula phase = (time difference / period) * 360 degrees to calculate the phase between the two waves.

2. Can the phase between sine waves be negative?

Yes, the phase between sine waves can be negative. This occurs when the two waves are out of phase, meaning they do not align at the same point in time. In this case, the phase would be represented by a negative angle, typically between -180 degrees and 0 degrees.

3. How does the frequency of the sine waves affect the phase difference?

The frequency of the sine waves does not directly affect the phase difference. However, a higher frequency means the waves complete more cycles in a given time, which can make it more challenging to accurately determine the phase difference based on time alone.

4. Is there a difference between phase and phase difference?

Yes, phase and phase difference are two different concepts. Phase refers to the position of a wave at a specific point in time, while phase difference refers to the difference in phase between two waves at a given time. Phase difference is often used to compare the alignment of two or more waves.

5. Can you calculate the phase between sine waves without knowing the time difference?

No, in order to calculate the phase between sine waves, you need to know the time difference between the waves. Without this information, you cannot accurately determine the phase difference between the two waves.

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