In a plane electromagnetic wave,the electric field oscillates with a frequency $2 \times 10^{10} \,s^{-1}$ and amplitude $40 \,Vm^{-1}$. The energy density due to the electric field is (given $\varepsilon_0 = 8.85 \times 10^{-12} \,Fm^{-1}$):

• A
  $1.52 \times 10^{-9} \,Jm^{-3}$
• B
  $2.54 \times 10^{-19} \,Jm^{-3}$
• C
  $3.54 \times 10^{-9} \,Jm^{-3}$
• D
  $4.56 \times 10^{-9} \,Jm^{-3}$