when an electric charge is moving in free space :-
a. only electric field produced
b. only magnetic field produced
c. both electric and magnetic produced
d. neither electric nor magnetic field produced
please give explanation as well
Answers
༒࿐៚ Answer ༒࿐៚
Option C. both electric and magnetic produced.
Explanation :-
The special theory of relativity when combined with electrostatics can give us the answer as to what a moving charge produced. We know that statically charged particles produce electric fields. Therefore, let us assume a wire having an infinite charge observed through the initial frame. Now, let the positive charges be flowing to the right and an equal number of negative charges be flowing to the left. Now, the net electric field will be zero as the total charge at any point is zero. Therefore, if an electron is placed next to this wire, it will experience no force. Now assume that we are moving past the wire with constant acceleration to the right on a rocket. Now, the relative motion of the charge and the rocket causes the negative charge to be length contracted and the positive charge be length expanded. Therefore, at any given point in the accelerating rocket frame, the negative charge will be more than the positive charge. These charges will now repel each other. However, the special theory of relativity states that both frames are valid and should agree that the electron does not accelerate towards or away from the line. This contradiction can be overcome by assuming a new force is generated when the electron is moving. Therefore, we can say that the moving charge produces both electric and magnetic fields.