Fourier Transform of exponential and heaviside function

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SUMMARY

The Fourier transform of the function φ(t) = e^(-at)H(t), where H(t) is the Heaviside step function, is computed by integrating the function from 0 to infinity. The Heaviside function effectively limits the integral's bounds, as it is defined to be 0 for negative t and 1 for positive t. The Fourier transform is defined as ∫_{-∞}^∞ f(t) e^{2 π i t ω} dt, which simplifies to ∫_{0}^∞ e^(-at) e^{2 π i t ω} dt when incorporating H(t). This results in a solvable integral that yields the Fourier transform of the given function.

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Homework Statement


Compute the Fourier transform of

\phi(t)=(e^(-at))H(t)

where H(t) is the Heaviside step function


Homework Equations





The Attempt at a Solution


I am stuck in an attempt at the solution, I am confused at how the heaviside step function factors in and think that it may just affect the upper and lower limits of the integral, but am not sure. I am looking for direction on how to approach the problem or at least set it up.
 
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The Fourier Transform is defined on a function f(t) as:

\int_{-\infty}^\infty f(t) e^{2 \pi i t \omega} dt

Now, try plugging in f(t)=e^(-at)H(t) into this definition. Remember that H(t) is defined to be 0 for all negative t and 1 for all positive t, so try splitting the integral into two integrals: one with lower bound -infinity and upper bound 0, and the other with lower bound 0 and the upper bound infinity. Then apply the definition of H(t) and it should become easy.
 

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