electrical week 5 revision

equation of magnetic field strength, H, is

Flux density equation is

permeability equals

ferromagnetic ring around a wire

• decreases magnetic field

• increases flux

• increases magnetic flux strenght

• increases magnetic field

When a current-carrying wire is formed into a coil

• the magnetic field is concentrated

• the flux increases

• there is alternating current

• potential difference is produced

For a coil of N turns, the m.m.f. (F) is given by

the field strength is

reluctance S is

• a measure of alternating current

• a measure of how the circuit opposes the flow of magnetic flux

• a measure of magnetic strenght

• a cause that happens in coils