Q6 of 30 Page 339

The sunlight reaching the earth has maximum electric field of 810 V m–1. What is the maximum magnetic field in this light?

Given: Maximum electric field E0 = 810 V m-1.


The sunlight travels through vacuum in outer space to reach the earth. The magnetic field and electric field are related to each other and their relation is



where E0 is the amplitude of the electric field, C is the speed of light in vacuum and B0 is the amplitude of maximum magnetic field.


Thus the maximum magnetic field is



The maximum magnetic field is 2.7 μT.


More from this chapter

All 30 →
4

Consider the situation of the previous problem. Define displacement resistance Rd = V/id of the space between the plates where V is the potential difference between the plates and id is the displacement current. Show that Rd varies with time as

Rd = R (et/τ – 1)


 5

Using B = μ0 H find the ratio E0/H0 for a plane electromagnetic wave propagating through vacuum. Show that is has the dimensions of electric resistance. This ratio is a universal constant called the impedance of free space.

 7

The magnetic field in a plane electromagnetic wave is given by

B = (200 μT) sin [(4.0 × 1015 s–1) (t –x/c)].


Find the maximum electric field and the average energy density corresponding to the electric field.


 8

A laser beam has intensity 2.5 × 1014 W m–2. Find the amplitudes of electric and magnetic fields in the beam.