Magnetism Flashcards
what are soft magnetic materials?
magnetise easily and lose magnetism easily
what are electromagnets?
coil wrapped around soft iron core
when current is given the iron gains/loses magnetism quickly
what is the magnetic field strength dependent on?
current - increase - stronger field strength
distance - closer to wire - “
magnetic materials surrounding wire
what is the motor effect?
current carrying wire placed in a magnetic field experiences a force
when is there maximum force?
when current is perpendicular to magnetic field
what is fleming left hand rule?
thumb - Force
index finger - magnetic direction
middle finger - current
F = B*?
I * L
B being magnetic field strength in tesla
L being length of wire in metres
what is motor effect used in DC motors for?
turning effect
what des more field lines being cut mean ?
stronger magnet
and greater voltage induced
what does a AC generator do?
coil rotating in a magnetic field causing coil to always cut field lines
to induce a voltage
how can the amplitude of AC be increased?
rotating coils more rapidly
increase magnetic field strength
increase turns
increase area
what are STEP- UP transformers?
increase voltage and decrease current to reduce energy loss
eg: power station to national grid
what are step down transformers?
decrease voltage and increase current
more safer at homes
how many percent efficient are transformers?
100%
