Question

1.  How is the direction of the magnetic field that accompanies a changing electric field related to the direction of the changing electric field?

2. What is the main difference between the effects of electric fields on charged particles and the effects of magnetic fields on charged particles?

3. What is the relationship between the magntidue of the electric and magnetic fields for an electromagnetic wave pulse traveling in vacuum? And how is the direction of B that accompanies a changing E related to the direction of the changing E field?

Answer 1

(1) The magnetic field that accompanies a changing electric field is in such a direction, that it can oppose the effect produced by the changing electric field. That means, the magnetic field will be created in such a way, that can reduce the effect of the changing electric field. This is known as Lenz's law.

(2) Main difference between electric fields and magnetic fields acting on a charged particle is, electric fields can exert a net force and hence can accelerate the charge particle along the direction of the electric field lines, whereas, magnetic field lines can not accelerate amy charge particle, instead, it can change the direction of motion of the charged particle.

(3) If the magnitude of electric and magnetic fields are E and B respectively, and c be the speed of light in vacuum, then the relationship between E and B is : E = ( B x c ).

The magnetic field that accompanies a changing electric field is in such a direction, that it can oppose the effect produced by the changing electric field. That means, the magnetic field will be created in such a way, that can reduce the effect of the changing electric field. This is known as Lenz's law.