Answer
$6.37\times10^{-5}J$.
Work Step by Step
The intensity of the electromagnetic wave is $I=\epsilon_0cE^2_{rms}$. The total energy passing through an area A during a time t is $IAt$.
$$E=\epsilon_0cE^2_{rms}At=(8.85\times10^{-12}F/m)(3.00\times10^8m/s)(0.0400V/m)^2(0.500m^2)(30.0s)$$
$$E=6.37\times10^{-5}J $$
