1. Forces On Moving Charges

2. Since current consists of e moving through wire, we might expect that any charged particle will also experience a force when moving through a magnetic field

3. Equation I = q/t l = vt F = I l B sin  F = (q/t) (vt) B sin 
F = q v B sin 
Greatest at 90º
Force zero if moving parallel to mag field

4. Right Hand Rule Works for negative particles, opposite for + particles
Fingers point in direction of the motion (v), and thumb in direction of B, palm faces direction of force

5. Example
A proton having a speed of 5.0 x 10-6 m/s is in a magnetic field and feels a force of 8.0 x N west when it is moving up. When moving horizontally (N) it feels no force. What is the magnitude and direction of the field?

6. Path Effects
In a magnetic field, the path of a charged particle is circular
Moves clockwise if negative
Moves counterclockwise if positive
If not totally perpendicular to the field, the circular path will be a spiral

7. Example
An electron travels ant 2.0 x 107 m/s perpendicular to a .010 T magnetic field. Describe its path. What is radius?