Interactions between Electricity and Magnetism Interactions between electricity and magnetism all involve some motion of either charges (electricity) or changes in the magnetic field.

Mag/Elec Interactions Magnetic Force The first idea is about a strange Force.  There is a magnetic force whenever a charge (or charged object) moves across a magnetic field.  The Force direction obeys the “Right Hand Rule #1” (of science)  The equation for this is F = q v B q = amount of charge (C), v = velocity, B = magnetic field (Teslas)

Magnetic Force on moving charge Moving charge must cross the magnetic field to experience a Force

Mag/Elec Interactions Right Hand Rule # 1  Point fingers in direction of moving charge q  Orient your palm so it’s facing the direction of the magnetic field B  Extend your thumb, it’s the direction of the force. In the above example the force is into the board or away from you.  This force happens only when the charge moves perpendicular to the magnetic field B.

Right hand rule for magnetic force

Right Hand Rule # 1 for Magnetic Force Practice this one.

Electric/Magnetic Idea #2: a moving charge (or current) creates a magnetic field A wire carrying a current creates it’s own magnetic field. This field is circular and its orientation is determined by Right hand rule #2

Mag/Elec Interactions Right Hand Rule # 2: to determine the direction of the circular magnetic field around a wire carrying a current. Direct your thumb along the wire in the direction of the current. Your fingers curl in the direction of the circular magnetic field

Mag/Elec Interactions Electro-magnets  If you coil a wire into a helical form (like wrapping a wire around a cylinder) and run a current through it, each circular coil creates a small mag field.  The mag field from each coil “adds up” to create what looks like a magnet with a North and South pole.  By running a current through this wire, you “make” a magnet. This is also known as a solenoid.