If the rms value of the electric field is 9.0 V/m at a distance of 6.0 m from an isotropic source, what is the rms value of the magnetic field at a distance of 12 m from the source? A) 3.0 × 10⁻⁸ T B) 1.5 × 10⁻⁸ T C) 0.75 × 10⁻⁸ T D) 0.38 × 10⁻⁸ T E) 0.19 × 10⁻⁸ T

Question

Quizplus · Accepted Answer

Using the relationship between electric and magnetic fields in free space, we have:

B = E/c

where c is the speed of light. At a distance of 6.0 m, the electric field has an rms value of 9.0 V/m, so the magnetic field at a distance of 12 m must be:

B = E/c = (9.0 V/m)/(3.0 × 10^8 m/s) × 12 m

B = 1.5 × 10^-8 T

Therefore, the answer is choice B.

If the Rms Value of the Electric Field Is 9