Download Magnetic force on a current element

Magnetism
Alternating-Current Circuits
Alternating Current Generators
A coil of area A and N turns rotating with constant angular velocity in a uniform
magnetic field produce a sinusoidal emf
Alternating current motor
Instead of mechanically rotating, we can apply an ac potential difference generated
by other ac generator to the coil. This produces an ac current in the coil, and the
magnetic field exerts forces on the wires producing a torque that rotaes the coil.
The magnetic field.
Magnetic forces on a moving charges.
Magnetic forces on a current element
Torques on current loops and magnets
The Magnetic Field
Magnets
The Earth is a natural magnet with
magnetic poles near the north and
south geographic poles.
The Magnetic Field
Magnets
Does exist an isolated
magnetic pole?
The SI units of magnetic
field is the tesla [T]
Earth magnetic field is
about 10-4 T
Powerful laboratory
produce fields of 1 -2 T as
maximum
1 Gauss [G] = 10-4 Tesla [T]
The Magnetic Field
The Magnetic Field. Magnetic force on a moving charge
A proton is moving in a region of crossed fields E =
2x105 N/C and B = 3000 G, as is showed in the figure.
(a) What is the speed of the proton if it is no deflected.
(b) If the electric field is disconnected, draw the path
of the proton
The Magnetic Field. Magnetic force on a current element
In the case of a straight segment
of length L
The Magnetic Field. Torques on Current loops and
Magnets
B
A current-carrying loop
experiences no net force in a
uniforme magnetic field, but it
does experience a torque that
tends to twist the loop
A circular loop of radius 2 cm has 10 turns of wire and carries a current of 3 A. The
axis of the loop makes an angle of 30º with a magnetic field of 8000 G. Find the
magnitude of the torque on the loop.
Sources of Magnetic Field
The Magnetic Field of Moving Charges
The Magnetic Field of Currents. The BiotSavart Law
The Magnetic Field Due to a Current loop
Sources of Magnetic Field
Moving Point Charges are the source of Magnetic Field
Sources of Magnetic Field
A solenoid is a wire tightly wounded into a helix
of closely space turns . A solenoid is used to
produce a strong, unifrom magnetic field in the
region surrounded by the loops
Inside a long
solenoid
Find the magnetic field at the center of a solenoid
of 600 turns that carries a current of 4 A
Sources of Magnetic Field: Solenoid and magnets
Left: Magnetic field lines of a solenoid; right Magnetic field
lines of a bar magnet
Magnetic Induction
Magnetic Flux
Induced EMF and Faraday´s Law
Lenz´s Law
MAGNETIC INDUCTION
The induced emf is in such direction as to
oppose, or tend to oppose, the change that
produces it.
Lenz´s Law
Alternating Current Generators
A coil of area A and N turns rotating with constant angular velocity in a uniform
magnetic field produce a sinusoidal emf
Alternating current motor
Instead of mechanically rotating, we can apply an ac potential difference generated
by other ac generator to the coil. This produces an ac current in the coil, and the
magnetic field exerts forces on the wires producing a torque that rotaes the coil.
29-2
Alternating Current in a Resistor
29-3
Alternating Current Circuits
29-4
Phasors
29-5
LC and RLC Circuits Without
a Generator
29-6
Driven RLC Circuits
29-7
The Transformer
Problems