Principles of Electromechanics

Electricity Motion

Electricity Motion: Motor

Motion Electricity: Generator

Magnetic Field & Faraday’s Law

Magnetic Field

1. Generation of magnetic field• Permanent Magnet:

• Electric Current: using right hand rule to determine the field direction

• Straight current

• Current coil

N

S

Current Motion: Current in magnetic field

• Magnetic field will exert a force on a current

• Magnetic field will exert a force on a moving charge

(N/m) BIL

F

× × × × × × × × × × × ×× × × × × ×× × × × × ×× × × × × ×× × × × × ×× × × × × ×

I

F

× × × × × × × × × × × ×× × × × × ×× × × × × ×× × × × × ×× × × × × ×× × × × × ×

-qV

FrqVB

qVBF

BVqF

B

B

sin

Circular Motion: Plane B

× × × × × × × × × × × ×× × × × × ×× × × × × ×× × × × × ×× × × × × ×× × × × × ×

-qV

Fr

Circular path: V||=0 Helical path: V||0

Charges in B field: Applications

Mass Spectrometer:Cyclotron (accelerator)

Example: Rail Gun

Acceleration: 5 106 gFinal speed: 1 km/sDuration: 1 ms