No problem, happy to help! Keep up the good work.

In summary, phase shift is the amount that a curve is shifted left or right from its zero-phase position. This can be seen by comparing a standard sine curve to the given graph. The phase shift in this case is about 3/4 of a period or 270 degrees. It is important to convert the period into seconds when calculating the frequency in Hertz.
  • #1
Rola
7
0
What is the meaning of phase and phase shift??


and How can I obtain phase shift from the sine curve ??


http://www12.0zz0.com/2009/01/16/17/965512159.jpg [Broken]


Note : I'm a begginer in physics , so please if you can , please explain the concept in details ..

Thank you ..
 
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  • #2
Thread moved to Homework Help. Welcome to the PF, Rola. Phase shift is how much that curve is shifted left or right of a zero-phase position.

The curve you're drawn is a cosine curve, since it is at max positive amplitude when the argument is zero. If you shift that drawing to the right by 1/8 of a wavelength, you would have a sin() curve. If you plot sin() and cos() on the same graph, you will see that the phase of the two is different (sifted) by PI/4.
 
  • #3
You can explore this on a graphing calculator.
Graph y = sin(x)
Then graph y = sin(x - 30) in degree mode. If using radians, replace 30 with pi/6.
You should see a 30 degree shift to the right. Play around with other negative and positive numbers until you have the feel of it.
 
  • #4
I understand the concept of phase shift..

but in this graph how can I know the zero-phase position??
 
  • #5
Rola said:
I understand the concept of phase shift..

but in this graph how can I know the zero-phase position??

I'd assumed that your sin(0) was the "zero phase". If that is a plot of a cos() function, then there is a phase shift in the function cos(theta - phase).

Phase is relative to the generating function. What equation did you use to plot your graph?
 
  • #6
Do you mean that you make comparison between standard sine curve and the graph ..

because in my book they write

phase shift =1/4*2pi=pi/2

but I don't know why they make this ..

I attached the file that contain the question ..

and if you can can tell me if mu solution to the question in red color true
 

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  • #7
I can't see the Word document you attached yet.
In the graph in the first post, 360 degrees or 2 pi radians is the width of one complete oscillation - from 0 to 12.5 where the dashed vertical line is located. So the question you must ask is: how far has it been shifted to the right? The basic sin() curve begins at the origin (height zero) and goes up from there. That place has been shifted to the right about 9 of the units on the horizontal axis. In degrees, it is shifted about 9/12.5 or 3/4 of 360 degrees. The phase shift is normally expressed as an angle regardless of what units you have on the x axis.
 
  • #8
Rola said:
Do you mean that you make comparison between standard sine curve and the graph ..

because in my book they write

phase shift =1/4*2pi=pi/2

but I don't know why they make this ..

I attached the file that contain the question ..

and if you can can tell me if mu solution to the question in red color true

I approved the attachment.

In the attachment, be careful in your frequency calculation -- you are right that the period is 12.5 hours, but the units of 1/T are not seconds unless you do a conversion...

I only skimmed the rest, but it looks like you are on the right track.

Delphi -- could you please check it now? Thanks.
 
  • #9
Yes, it all looks good except for that one place where you must convert the period into seconds before computing the frequency in Hertz. In the good old days, we used "cycles per second" instead of Hertz!
 
  • #10
berkeman said:
I approved the attachment.

In the attachment, be careful in your frequency calculation -- you are right that the period is 12.5 hours, but the units of 1/T are not seconds unless you do a conversion...

I only skimmed the rest, but it looks like you are on the right track.

Delphi -- could you please check it now? Thanks.

Delphi51 said:
Yes, it all looks good except for that one place where you must convert the period into seconds before computing the frequency in Hertz. In the good old days, we used "cycles per second" instead of Hertz!


Thank you very much for helping me..
 

1. What is a phase shift in a sine curve?

A phase shift in a sine curve is a horizontal shift of the graph to the left or right. It represents a change in the starting point of the curve, where it intersects with the x-axis. This shift can be caused by a change in the frequency or period of the curve.

2. How is phase measured in a sine curve?

Phase is measured in radians in a sine curve. It is a unit of angular measurement that is used to describe the position of a point on the curve relative to its starting point.

3. What is the difference between phase and frequency in a sine curve?

Phase and frequency are two different properties of a sine curve. Phase refers to the horizontal shift of the curve, while frequency refers to the number of cycles or repetitions of the curve per unit of time. They are both important in understanding the behavior of a sine curve.

4. Can a phase shift affect the amplitude of a sine curve?

Yes, a phase shift can affect the amplitude of a sine curve. When the curve is shifted to the left or right, the amplitude may increase or decrease depending on the direction of the shift. This is because the starting point of the curve affects the overall shape and size of the curve.

5. How does a phase shift affect the period of a sine curve?

A phase shift can change the period of a sine curve. If the curve is shifted to the left or right, the period may increase or decrease. This is because the starting point of the curve determines how long it takes for the curve to complete one full cycle.

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