Choose the incorrect statements from the following:
(A) The energy density of an electric field in electromagnetic waves is $(ε_0E^2/2)$,
(B) The total energy of electromagnetic waves falling on a surface is $6.0 × 10^5 J$ and the momentum delivered to the surface, if absorbed fully, is $2×10^3\, kg\, m/s$,
(C) The speed of the electromagnetic waves is $E_0/B_0$
(D) The energy density of magnetic field in electromagnetic Waves is $(B^2/μ)$
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (B) and (D) only
Analyze each statement:
(A) Correct — Energy density of electric field: $u_E = \frac{1}{2} \epsilon_0 E^2$
(B) Inorrect — Momentum delivered $p = \frac{U}{c} = \frac{6.0 \times 10^5}{3 \times 10^8} = 2 \times 10^{-3} \ \text{kg·m/s}$, not $2 \times 10^3$
(C) Correct — Speed of EM wave: $c = E_0/B_0$
(D) Incorrect — Energy density of magnetic field: $u_B = \frac{B^2}{2 \mu_0}$
Incorrect statements: (B), (D)