p7- electromagnets Flashcards
how is a magnetic force created around a wire?
when a current flows through
what makes the magnetic force stronger in a wire?
higher current, the closer you are to it.
(affected by current and distance from wire)
what is the field made up of?
concentric circles perpendicular to the wire, with the wire at the centre
what is the right hand rule? what does it entail?
when you put your right hand up with your thumg up and fingers curled. THUMB represents DIRECTION of CURRENT. and your fingers represent the magnetic field direction.
what happens when your thumb is up (direction of current)? NORMAL
ANTI-CLOCKWISE
what happens if you reverse current?
magnetic field changes direction?
what direction is magnetic field if your thumb is down?
CLOCKWISE
what does a circle with a cross represent (current)?
CURRENT IN TOWARDS PAGE (clockwise)
what does a circle with a dot represent (current)?
CURRENT OUT OF THE PAGE (anti-clockwise)
what is a soleniod?
a coil of wire with current running through it
what does a solenoid do?
increase strength of magnetic field that a wire produces.
what causes a solenoid to increase magnetic field?
field lines around each loop of wire line up with each other, resulting in lots of field lines pointing in the same direction that are very close to each other.
what do closer field lines mean?
stronger field
what is the magnetic field inside a solenoid like?
STRONG & UNIFORM
what is the outside of a solenoid like?
the ends of a solenoid act like a north pole and south pole of a bar magnet.
how to increase the field strength of a solenoid? why does it increase?
IRON block in centre of coil, as iron core becomes an INDUCED magnet when CURRENT flows through it.
what happens if you stop the current in a solenoid?
the magnetic field disappears
what is a solenoid with an iron core in it called?
(magnetic field can be turned on and off)
ELECTROMAGNET
what are some uses of an electromagnet?
(3)
RECYCLING PLANT, SCRAPPED CRANE, ELECTRIC BELL, circuit breaker, relay switch
What is a recycling plant?
large electromagnet used on recycling plant conveyor belt to pick up & move metal cans
what is a SCRAPYARD CRANE?
items are picked up when the electromagnet is on & dropped when off. Useful as they’re strong to pick up heavy metal (cars)
what is a ELECTRIC BELL?
switch on: electromagnet turns on & metal arm attracted to gong arm no longer connected to circuit. switch off: arm returns to original position
