1. Biot-Savart Law: B field from a current
Refer p. 689 for straight wire
Right hand rule for direction
i=100 A, R=10 m
B=210-6 T = 210-2 Oe (earth field)
Again superposition principle is still valid

2. Example: Rail Gun Acceleration: 5  106 g Final speed: 1 km/s
Duration: 1 ms

3. Ampere’s Law Gauss’ law Ampere’s Law
Quantitative relationship between electric field (direction and magnitude) on a CLOSED SURFACE (Gaussian surface) and total charges inside the Gaussian surface.
Quantitative relationship between magnetic field (direction and magnitude) on a CLOSED LOOP (Amperian Loop) and total current passing through the Amperian loop.

4. Ampere’s Law: Continues
Define dS
2. Assign sign to current using RH rule
fingers  Amperian loop (dS)
direction of outstretched thumb  +i
opposite  -i