In an inertial frame of reference, the magnetic force on a moving charged particle is F
Its value in another inertial frame of reference will be
(a) remained same
(b) changed due to change in the amount of charge
(c) changed due to change in velocity of charged particle
(d) changed due to change in field direction"
Answers
Explanation:
The resolution to this paradox is that the electric and magnetic fields need to be transformed when you change from one inertial frame to another, through rules fixed by special relativity. This is explained in this Wikipedia page or in your favourite EM textbook's relativity section, but the short of it is that in the frame transformation you describe, the magnetic field is tranformed into an electric field given by
E′=γu×B,
where u is the velocity of the new frame with respect to the old one and γ=1/1−u2/c2−−−−−−−−√. This new electric field acts on the particle to fully cancel out the effect of the magnetic force it feels on the new frame - electric and magnetic fields change from one inertial frame to the next, but if the total force is zero in one frame it must be zero in all frames.