Magnetism Flashcards
(14 cards)
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%
