plz help..urgent!?

Question

There are two fields- magnetic and electric which are parallel to each other. If a particle is placed on the magnetc field, what would be the direction of this particle.(how would it move)

sorry.. what is the motion of the charged particle placed between these fields?

Answer 1

This question is somewhat vague but I'll do my best to answer it. When you say the particle is placed "on the magnetic field" I'll assume you mean it is under the influence of the electric field as well and the initial velocity of the particle is zero. I'll further assume this is a charged particle otherwise the answer is trivial.

Remember that the magnetic force vector is the cross product of magnetic induction with the product of the charge and velocity of the particle. If the initial velocity is zero, then the magnetic force is initially zero as well. So initially, the particle will move parallel to the electric field up or down depending on the polarity of the charge on the particle.

As the particle starts to move, the magnetic field will impart a force on the particle at a right angle to its direction of motion. So the particle will curve outside the plane of the two fields.

If you want an actual equation of motion you will need to be specific about the charge on the particle and the electric and magnetic field strength.

I hope this helps.

adendum
Again, I'm not sure I understand you correctly. If the particle is placed "between" these fields does that me the field strength at the position of the particle is zero? In that case the particle won't move at all.