An electromagnetic wave of frequency 1 × 1014 hertz is propagating along z - axis. The amplitude of electric field is 4 V/m. If ϵ0 = 8.8 × 10-12 C2/N-m2 then average energy density of electric field will be :

Question

An electromagnetic wave of frequency 1 × 1014 hertz is propagating along z - axis. The amplitude of electric field is 4 V/m. If ϵ0 = 8.8 × 10-12 C2/N-m2 then average energy density of electric field will be : (A) 35.2 × 10-10 J/m3 (B) 35.2 × 10-11 J/m3 (C) 35.2 × 10-12 J/m3 (D) 35.2 × 10-13 J/m3

Tardigrade Admin · Accepted Answer

Energy density is given as: e=(ϵ0 E2/2)=8.8 × 10-12 × 8 =70.4 × 10-12 (J/m3) Therefore, average energy density = e / 2=35.2 × 10-12 J / m 3.

Q. An electromagnetic wave of frequency $1 \times 1 0^{14}$ hertz is propagating along z - axis. The amplitude of electric field is 4 V/m. If $ϵ_{0} = 8.8 \times 1 0^{- 12} C^{2} / N - m^{2}$ then average energy density of electric field will be :

$35.2 \times 1 0^{- 10} J / m^{3}$

$35.2 \times 1 0^{- 11} J / m^{3}$

$35.2 \times 1 0^{- 12} J / m^{3}$

$35.2 \times 1 0^{- 13} J / m^{3}$

Energy density is given as:
$e = \frac{ϵ _{0} E ^{2}}{2} = 8.8 \times 1 0^{- 12} \times 8$
$= 70.4 \times 1 0^{- 12} \frac{J}{m ^{3}}$
Therefore, average energy density
$= e /2 = 35.2 \times 1 0^{- 12} J / m^{3}$ .

Q. An electromagnetic wave of frequency 1×1014 hertz is propagating along z - axis. The amplitude of electric field is 4 V/m. If ϵ0​=8.8×10−12C2/N−m2 then average energy density of electric field will be :

35.2×10−10J/m3

35.2×10−11J/m3

35.2×10−12J/m3

35.2×10−13J/m3