1. Electromagnetic Force

2. Force on a Charged Particle
F= Bqv
F=force (N) B= Magnetic field
q= charge (C) N/Amp∙m or
velocity (m/s) Tesla

3. 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

4. Force on a Wire With Current
F=BIL
F- force(N) B- Magnetic Field
I-current(amps) (N/A∙m) or Tesla
L-length(m)

5. 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

6. B = 0.4N/A∙m I S N
F =0.20N

7. 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 S N C A F D F
Point (A)- Current is outward
Points (B) and (D)- no current, force is parallel to field
Point (C)-Current is into the wire

8. Graphing Alternating Current
IMax A A B B D t D
-I max C C
*Commercial frequency is 60Hz so current changes direction 120 times per second!

9. Diode- Converts AC to DC by limiting the direction of the current flow

10. Graphing Direct Current
I max t
Doesn’t change direction

11. Generator-Rotating loop in a magnetic field that produce a current
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.
The current changes direction due to the loop in the wire. F

12. Motor-Uses a current in a magnetic field to generate a force
Motor-Uses a current in a magnetic field to generate a force. This force allows work to be done by the motor.