## zhiyuan3yu5 3 years ago In which direction does a magnetic force act on an electron that is moving in the positive x-direction in a magnetic field pointing in the positive z-direction? A) any direction in the xy-plane B) the negative y-direction c) the negative x-direction D) the positive y-direction a particle with charge q is at rest when a magnetic field is suddenly turned on. The field points in the z-direction. What is the direction of the net force acting on the charged particle? a) In the z-direction. b) There is no force on the particle. c) In the y direction d) In the x direction

1. imron07

The direction of magnetic force is the same as vextor v x B direction. It follows right hand rule, so postive x X positive z = negative y direction. F=qE. The force direction follows magnetic field E direction. Hence a)

2. ghazi

\[F=q*(V*B)\] take the cross product of the movement of electron and applied magnetic field

3. AERONIK

there is no force acting on the particle in the second question as the magnetic force acts only on those particles which are in motion.

4. timo86m

use right hand rule

5. imron07

@AERONIK : the magnetic force is changing (from zero then turned on).

6. zhiyuan3yu5

i did the right hand rule for the first one and got neg y as well. for the 2nd question, is it b? no net force?

7. Ninalynn

Actually yes I think its B

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