1. Magnetic Fields Produced by Currents February 14, 2007

2. Moving Charges Produce Magnetic Fields “moving charges” = “current” Right hand rule for currents (RHR-2): Thumb in direction of current, fingers curl in direction of B-field. I r B Long, straight wire

3. I2LI2L r RHR-1: Fingers along B Thumb along v Palm shows F (eqn 21.3 in book) I1I1 Example: Two Wires (opposite directions)

4. I2LI2L RHR-1: Fingers along B Thumb along v Palm shows F (eqn 21.3 in book) I1I1 Example: Two Wires (same direction) r

5. Loop of Wire (N=1 turn) RHR-2 Thumb along current I Fingers curl along B Loop with N Turns: Current I B

6. Adding Loops of Wire (same radius) X 1X 2X 3X 4 Loop with N Turns

7. The Solenoid II Similar (but not exactly the same) to adding N turns of wire with equal radius: B But let’s just call B-field through solenoid L