Transcript Interactions between Electricity and Magnetism

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
 There is a magnetic force whenever a
charge (or charged object) moves across a
magnetic field.
 The Force direction obeys the Right hand
rule we discussed in class.
 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
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.
 This force happens only when the charge
moves perpendicular to the magnetic field B.
Right hand rule for
magnetic force
Mag/Elec Interactions
 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.