Question

Which expression gives the intensity of an electromagnetic wave in terms of its electric-field amplitude?

Options

• \[I=\frac{1}{2}c\varepsilon_0E_0^2\]

• \[I=2c\varepsilon_0E_0^2\]

• \[I=\frac{1}{2}c\varepsilon_0E_0\]

• \[I=\frac{E_0^2}{2c\varepsilon_0}\]

Answer 1

Intensity is given by \[I=\frac{1}{2}c\varepsilon_0E_0^2\]. The electric-field amplitude is squared, so the expression depends on \[E_0^2\].