Question

The sunlight reaching Earth has maximum electric field of 810 Vm⁻¹. What is the maximum magnetic field in this light?

Answer 1

Given:
Electric field amplitude, E₀ = 810 V/m
Maximum value of magnetic field = Magnetic field amplitude = B₀ = ?
We know:
Speed of a wave =$\frac{E}{B}$
For electromagnetic waves, speed = speed of light
B₀ = µ₀ ε₀ cE₀
Putting the values in the above relation, we get:
$$\begin{gathered} B_0=4\mathrm{\pi }\times {10}^{-7}\times 8.85\times {10}^{-12}\times 3\times {10}^8\times 810 \\ {B}_0=4\times 3.14\times 8.85\times 3\times 81\times {10}^{-10} \\ {B}_0=27010.9\times {10}^{-10} \\ {B}_0=2.7\times {10}^{-6}\mathrm{T}=2.7\mathrm{\mu T} \end{gathered}$$