Energy in a signal

• Signals and Systems

Definition of Energy

Energy is the ability or potential for something to create change. Scientifically energy is defined as total work done by a force. Work can be mathematically calculated as the line integral of force per infinatesimal unit distance,

$W=\int \mathbf{F}\cdot \mathrm{d}\mathbf{s}$

Power represents a change in energy.

$P(t)=\frac{dW}{dt}$

This means we can also write energy as

$W=\underset{-\mathrm{\infty }}{\overset{\mathrm{\infty }}{\int }}P(t)dt$

Energy of a signal

From circiut analysis we know that the energy of a voltage source is,

$W=\frac{{\mathbf{V}}^2(t)}{R}$

Assuming that R is 1 then the total energy is just,

$W=\underset{-\mathrm{\infty }}{\overset{\mathrm{\infty }}{\int }}|\mathbf{V}{|}^2(t)\mathrm{d}\mathbf{t}$

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