Question

The Dirac-delta function (δ(t - t0)) for t, t0 ∈ R, has the following property

a b ϕ ( t ) δ ( t t 0 ) d t = { ϕ ( t 0 ) a < t 0 < b   0 otherwise

The Laplace transform of the Dirac-delta function δ(t - a) for a > 0;  L ( δ ( t a ) ) = F ( s ) is

Options :

  1. 0

  2. esa

  3. e-sa

Show Answer

Answer :

e-sa

Solution :

Dirac Delta Function

δ ( t a ) = lim ϵ 0 { 0 , < t < a 1 ϵ , a t a + ϵ 0 , a + ϵ < t < ϵ

L[δ(t – a)] = e-as

∵ ∫ 0 f ( t ) δ ( t a ) d t = f ( a )

L [ δ ( t a ) ] = 0 e s t δ ( t a ) d t = e a s

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