What is the Fourier transform of sin(x) with non-zero terms?

  • #1
lys04
112
4
Homework Statement
Why is what I'm doing here not correct? (Because last line seems to give me 0) Could someone point me in the right direction please.
Relevant Equations
Fourier transform
1729514023111.png
 
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  • #2
1729516645362.png


This transformation seems incorrect because ##e^{-ikx}## is a complex number. How about checking it by substitution of [tex] \sin x = \frac{e^{ix}-e^{-ix}}{2i}[/tex]
 
Last edited:
  • #3
anuttarasammyak said:
View attachment 352508

This transformation seems incorrect because ##e^{-ikx}## is a complex number. How about checking it by substitution of [tex] \sin x = \frac{e^{ix}-e^{-ix}}{2i}[/tex]
Indeed, but more importantly it should also be realised that the primitive function is incorrect for ##k = 1##.
 
  • #4
anuttarasammyak said:
This transformation seems incorrect because e−ikx is a complex number
Ohh alright yeah that makes sense. Ty!
 
  • #5
Orodruin said:
Indeed, but more importantly it should also be realised that the primitive function is incorrect for k=1.
What does this mean?
 
  • #6
lys04 said:
What does this mean?
That your integration is wrong when k = 1.
 
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  • #7
Orodruin said:
That your integration is wrong when k = 1.
It's gonna be wrong for all k s.t e_-ikx has a real part?
 
  • #8
lys04 said:
It's gonna be wrong for all k s.t e_-ikx has a real part?
You are misunderstanding my comment. I said that apart from the fact pointed out by @anuttarasammyak in post #2, the integral is also wrong for ##k = 1##. This will be crucial to correct also when you have corrected the imaginary part error.
Orodruin said:
Indeed, but more importantly it should also be realised that the primitive function is incorrect for ##k = 1##.
(my emphasis)
 
  • #9
Oh, and on top of that, the last line is not equal to zero either. The sine terms have the same sign.
 

FAQ: What is the Fourier transform of sin(x) with non-zero terms?

What is the Fourier transform of sin(x)?

The Fourier transform of sin(x) is given by the formula: F{sin(x)}(ω) = (1/2j) [δ(ω - 1) - δ(ω + 1)], where δ is the Dirac delta function. This indicates that sin(x) has frequency components at ω = ±1.

What are non-zero terms in the Fourier transform of sin(x)?

The non-zero terms in the Fourier transform of sin(x) correspond to the delta functions at the frequencies ω = 1 and ω = -1. These terms indicate the presence of these specific frequency components in the signal.

How does the Fourier transform relate to the frequency of sin(x)?

The Fourier transform decomposes a time-domain signal into its constituent frequencies. For sin(x), which oscillates at a frequency of 1 Hz, the transform reveals that there are significant contributions at ω = ±1, reflecting the sinusoidal nature of the signal.

What is the significance of the Dirac delta function in the Fourier transform of sin(x)?

The Dirac delta function in the Fourier transform signifies that the signal sin(x) contains pure frequency components at specific points (ω = ±1) with no other frequencies present. This is characteristic of idealized sinusoidal signals, which are composed of single frequencies.

Can the Fourier transform of sin(x) be visualized? If so, how?

Yes, the Fourier transform of sin(x) can be visualized as two spikes on a frequency spectrum at ω = 1 and ω = -1, with the height of each spike representing the amplitude of the corresponding frequency component. This visual representation highlights the discrete nature of the frequency content of the sinusoidal signal.

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