A point source of electromagnetic radiation has an average power output of `800W`. The maximum value of electric field at a distance `3.5m` from the source will be `62.6 V/m`, the energy density at a distance `3.5 m` from the source will be- (in `"joule"//m^(3)`)

Explanation

Intensity of electromagnetic wave given is by
`I=(P_("av"))/(4pir^(2))=E_(m)^(2)/(2mu_(o)c)`
`E_(m) = sqrt((mu_(o)cP_("av"))/(2pir^(2)))=sqrt(((4pixx10^(-7))xx(3xx10^(8))xx800)/(2pixx35^(2)))=`
`62.6V//m`