Question

The intensity of the light from a bulb incident on a surface is 0.22 W/m2. The amplitude of the magnetic field in this light-wave is ___ × 10–9 T.

(Given : Permittivity of vacuum ε0 = 8.85 × 10–12C2N–1–m–2, speed of light in vacuum c = 3 × 108 ms–1)

Answer 1

The correct answer is: 43

$I=\frac{1}{2}ε_oE_0^2.c=\frac{1}{2}ε_0(cB_0)^2$

$⇒B_0≃43×10-T$