electromagnetic induction

magnetic flux linkage

magnetic flux density x area x number of turns

area is perpendicular to magnetic field

Lenz’s law

Direction of induced emf is such as to oppose the change causing it

Two situations charge particle in a mag field does not experience a force

Stationary/not moving

Parallel to the magnetic field

Tesla

Newton per ampere per metre

Magnetic flux density

Force per unit

Force per unit length of wire

Current normal to magnetic field

Magnetic field

Region where there is a force exerted on a moving charge

ref heating effect explains what is meant by rms value of an alternating current

direct current that produces the same heating effect as the alternating current

ref power dissipated in a resistor what is meant by rms value of an alternating voltage

constant voltage that produces same power as the mean power of the alternating voltage

Faradays law

induced emf proportional to rate of change of magnetic flux linkage

Force

BILsin theta

Magnetic flux density x current x length of wire in field x sin angle between wire and field

Hall probe

Measure mag field strength through volt

Must be perpendicular to field lines

Electrons are deflected as they move through

Conventional current flows

Downwards

Hall voltage formula

Vh = BI/nte

E = Vh / d

Velocity selector formula

BV = E

Direction of the resultant force on charged particle moving in circular path

Towards the centre

Force on charged particle moving through mag field depends on

Mag fly. Density and speed of the charged particle

South Pole current flows

Clockwise

North Pole current flows

Anticlockwise

Ideal transformer

0 loss

Transformer steps

1. Prim coil creates mag field taken on the soft iron core

2. Mag field continued inside second coil

3. Sec. Coil will oppose any charge in mag flux linkage in and around

4. Faradays law

5. So sec coil ends up with an induced emf created to oppose that change

Induce voltage is at max when

Flux is changing the most (90% or pi/2 rad out of phase)

Step up transformer

Ns > Np so Vs > Vp

Step down

Ns < Np so Vs < Vp

Transformer efficiency

VsIs / VpIp

EMF in AC generator

BANwsinwt

emf for solenoid

E = deltaBAN / delta t

mag flux density/calibrate a balance

BILx = mgy

Hall volt max and min

Max - perp

Min - parallel