EM/EMI Flashcards
A magnetic field is
A region of space in which a magnetic material, a current carrying conductor or a moving charge, located in it may experience a force
Formula for magnetic flux density (otherwise indicated as B)
(µoI)/(2pi*d) for current carrying conductor/solenoid
(µoI)/(2r) for a flat circular coil
(µoNI) for a solenoid
Magnetic flux density at a given point in a magnetic field is defined as
Force per unit length exerted of a long straight conductor carrying a unit current placed perpendicular to a uniform magnetic field.
Formula for magnetic force
BILsin(angle)
SI unit for magnetic flux density
1 tesla
Define tesla
The uniform magnetic force which, acting normally to a long, straight wire carrying a current charge of 1 Ampere, causes a force per unit length of 1Nm^-1 on the wire
Formula for centripetal force caused by magnetic force
(mv^2)/r = Bqvsin(angle)
Magnetic flux through a plane surface is
The product of the component of magnetic flux density normal to the surface and the area of the surface.
Define Weber
The magnetic flux through an area of 1m^2 when magnetic flux density perpendicular to the area is 1T.
The magnetic flux linkage through a loop/coil is
The product of the number of turns on the loop/coil and the magnetic flux density passing perpendicularly through the cross sectional area of the loop/coil
Faraday’s law of electromagnetic induction
Magnitude of the Induced e.m.f. is directly proportional to the rate of change of magnetic flux linkage
Lenz’s law of electromagnetic induction
Direction of induced e.m.f.. is such as to cause effects to oppose a change in the flux linkage that is inducing it
Formula for E (in this case the electromotive force for EMI) (there are 3)
Blv
NBAsin(angular velocity/time)
1/2 Br^2 (angular velocity)
State what is meant by a field of force
A region of space where a body experiences a force due to interaction with a field.
Determination of Magnetic flux density using current balance
Fbd1 = mgd2
BILd1 = mgd2
B = (mgd2)/ILd1
