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
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Magnetic Force
The first idea is about a strange Force.
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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
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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
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Right Hand Rule # 1
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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
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Practice this one.
Electric/Magnetic Idea #2: a moving
charge (or current) creates a magnetic field
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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
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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
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Electro-magnets
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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.