• A long straight wire carrying a current I creates a Magnetic Field around the wire in concentric circles. The direction of the magnetic field B is tangent to the circles.
• A modified right-hand rule can be used to determine the direction of B. With your thumb pointing along the direction of the positive current I flow, curl your fingers around the wire. The curl of your fingers point in the direction of B.

Biot-Savart Law:

• The current in every part of a wire makes a contribution to the magnetic field at a given location. Integrating along the line adds up the contributions from all the moving charges in the current carrying line.

	dB	= Differential size of the Magnetic Field at some location.(SI: T)
	mo	= 4p x 10 -7 T.m/A (Permeability of free space)
	I	= Current in wire. (SI: Amp)
	dl	= Differential section of wire. (SI: m)
	r	= Distance from the wire differential dl to the location. (SI: m)

Ampere's Law:

• Ampere's Law is magnetic field equivalent to Gauss's Law for electric field.
• The left hand side is the interval around a closed path.
• Ampere's Law states that if the closed path contains any current caring wires then the results of integration is equal to the total current inclosed in path of integration.
• For some highly symmetric charge distributions is possible to use Ampere's law to quickly find the magnitude of the B-field.