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Electrical Engineering QUESTION #2171
Question 1
The Fourier transform of $\text{rect}(t/\tau)$ is $X(f) = \tau\,\text{sinc}(f\tau)$. For $\tau = 1\,\text{ms}$, the first spectral null occurs at:
  • $f = 1\,\text{kHz}$✔️
  • $f = 500\,\text{Hz}$
  • $f = 2\,\text{kHz}$
  • $f = 100\,\text{Hz}$
Correct Answer Explanation
The first null of $\text{sinc}(f\tau)$ occurs at $f\tau = 1$, i.e., $f = 1/\tau = 1/10^{-3} = 1\,\text{kHz}$.