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Reading Quiz Your book primarily uses which of the following notations to represent the Fourier transform of f(t)? a. a. f( ) b. b. F {f(t)} c. c. FT{f(t)} d. d. g(t) e. e. g( )
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Announcements 2/22/12 Prayer Handouts, reading assignment for next
lecturea. Dirac delta functionb. Convolutions
Reading Quiz The Fourier transform method we will be
using most in this class involves:a. cosinesb. sinesc. complex exponentials
Reading Quiz Your book primarily uses which of the
following notations to represent the Fourier transform of f(t)?
a. f()b. F {f(t)}c. FT{f(t)}d. g(t)e. g()
Fourier transform of Gaussian wavepacket
T = 1.5, 0 = 10
Fourier transform of Gaussian wavepacket, cont.
T = 1.5, 0 = 10(original)
T = 3.5, 0 = 10(longer duration)
Fourier transform of Gaussian wavepacket, cont.
= 1.5, 0 = 10(original)
= 0.35, 0 = 10(shorter duration)
How to get single peaks in F.T.
Uncertainty Principle
Reading Quiz We learned that the time-averaged
intensity relates to the electric field as . What is this other, closely-related, quantity called?
a. dissipation spectrumb. frequency spectrum c. Parseval spectrumd. power spectrume. utility spectrum
20( , ) ( , )2n cI t E t
r r
20( , ) ( , )2n c
I E
r r
Thought question (ungraded) What are the units of I()?
a. intensityb. intensity/frequencyc. intensity/frequency2
d. intensity/timee. intensity/time2
If you care, the actual units of intensity are W/m2 and the units of frequency are s-1 (or more
technically rad/s). But you should be able to figure this question out without knowing any of that.
Parseval’s Theorem Example= 1.5, 0 = 10 (original)
|E(t)|2
|E()|2
Are the areas equal?