Question

instantaneous value of electric field in a region
where electromagnetic wave is propogating is E,
them instantaneous value of energy density in the
pace is , is peak value of electric field).​

Answer 1

Thus instantaneous value of energy density is "u" = 1/2 ε0E^2 + 1 B^2 / 2 μo  

Explanation:

• Energy density in electric filed is given as = 1/2 ε0E^2
• Energy density in a magnetic field = 1 B^2 / 2 μo
• As electromagnetic waves have dual nature, therefore;
• Total energy density"u" = 1/2 ε0E^2 + 1 B^2 / 2 μo  
• It is clear that the energy in the magnetic field is equal to the energy in the electric field.
• It can be written as:
• u = 1/2 ε0E^2 = 1 B^2 / 2 μo