AP EAPCET 25-Aug-2021 Shift 1 Paper

The average electric energy density of EM
wave in frec space, µE=

1

2

ε0E2
=

1

2

ε0[

E0

√2

]2
=

1

4

ε0E02 ...(i)
Average magnetic energy density of EM wave in free space,
µB=

1

2

B2

µ0

=

1

2

(

B0

√2

)2

1

µ0

=

B02

4µ0

...(ii)
Using relation, E0=cB0=

B0

√µ0ε0

...(iii)
From Eqs. (i), (ii) and (iii), we get
uE=uB
Hence, energy contributions of both electric and magnetic fields are equal.