Particle is moving a vacuum at speed 5 x 10^5 m/s in a direction perpendicular t
ID: 1792087 • Letter: P
Question
Particle is moving a vacuum at speed 5 x 10^5 m/s in a direction perpendicular to a uniform magnetic field of strength 4 x 10^-2 T. The charges on particle is 3.2x10^-9C and its mass is 6.6 x 10^-27 kg. as the particle moves, its velocity
1. decreases
2. is still perpendicular to the magnetic field
3. gains a component in the direction of the magnetic field
The answer is 2. But, I don't know how to understand this problem. Only thing that I know is that equation F= qvb is used to solve this problem. Could you explain this in easier way by using that equation?
Explanation / Answer
Assume a case for magnetic field moving into or out of a plane perpendicularly. If a particle moves in this plane, you can quickly see by Flemings left-hand rule that force is always directed in the plane of the particle. As this plane is perpendicular to the magnetic field, the motion is never caused in the direction of the magnetic field or opposite to it.