Answer:
The  value is  [tex]E =  8.9 *10^{-5} \  J[/tex]
Explanation:
From the question we are told that
  The  area is  [tex]A =  0.700 \  m^2[/tex]
  The  root mean square value  is [tex]E_{rms} =  0.0400 \  V/m[/tex]
  The time taken is [tex]t =  30.0 \  s[/tex]
Generally the energy is mathematically represented as
   [tex]E =  c *  \sepsilon_o *  A  *  t  * E_{rms}^2[/tex]
=> Â Â [tex]E = Â 3.0*10^{8} * Â 8.85*10^{-12} * Â 0.700 * Â 30 * (0.04)^2[/tex]
=> Â Â [tex]E = Â 8.9 *10^{-5} \ Â J[/tex]
  Â