Transcript Electromagnetic Force

Electromagnetic Force
Force on a Charged Particle
F= Bqv
F=force (N)
q= charge (C)
velocity (m/s)
B= Magnetic field
N/Amp∙m or
Tesla
EXAMPLE
An electron travels at a speed of 3x106m/s
through a magnetic field of 4x10-2 Tesla.
How much force is acting on the electron?
F=Bqv
F= (4x10-2T)(1.6x10-19C)(3x106m/s)
F= 1.9x10-14N
Force on a Wire With Current
F=BIL
F- force(N)
I-current(amps)
L-length(m)
B- Magnetic Field
(N/A∙m) or Tesla
Example
A wire 1.0m long carries 0.50amps of
current. If the force acting on the wire is
0.2N, what is the magnetic field strength
the wire experiences?
F=BIL
0.20N = B(0.5Amp)(1.0m)
B = 0.40 N/A∙m
B = 0.4N/A∙m
I
S
N
F =0.20N
Alternating current- Current that reverses direction
due to a force and a magnetic field acting on a wire.
*Use right hand rule
F
B
F
N
C
F
A
D
S
F
Point (A)- Current is outward
Points (B) and (D)- no current, force is parallel to field
Point (C)-Current is into the wire
Graphing Alternating Current
IMax
0
-I max
A
A
B
B
D
D
C
t
C
*Commercial frequency is 60Hz so current
changes direction 120 times per second!
Diode- Converts AC to DC by limiting the
direction of the current flow
I
t
Graphing Direct Current
I max
t
Doesn’t change direction
Generator-Rotating loop in a magnetic field
that produce a current. Current changes
direction every ½ cycle (AC).
F
An outside force
causes the wire loop
to rotate inside a
magnetic field.
F
The current changes
direction due to the loop
in the wire.
Motor-Uses a current in a magnetic field to
generate a force. This force allows work
to be done by the motor.