P4 Magnets and Magnetic Field

• Created by: Sagaana
• Created on: 02-05-18 13:45
• P4 Magnets and Magnetic Field
• Magnets and magnetic fields
• Magnets have a north pole and a south pole
• They have magnetic field lines they closer they are the stronger the Magnetic flux density
• You can see magnetic field line using compasses or iron filling (compasses all ways point north thus shows that the earth have a magnetic field
• like pole repel and opposite poles attracts.
• Electromagnetism
• A current caring wire has a Magnetic field around it
• If you have a lot of Solenoids together the magnetic effect increases
• You can increase the magnetic effects of a solenoid:-current increased -the number of turns -the length of the solenoid-and adding a magnetic Core inside.
• Magnetic Forces
• When two magnetic fields affect one another . the result is a force.To experience full force the wire has to be 90 degrees to the magnetic field
• Flemmings lefts hand Rule
• Thumb: Motion
• First Finger: Magnetic field
• Second Finger: Current
• Force= Magnetic Flux density x Current x Length
• Motors
• Current Increases so stronger Field and increases wire.which make the coil spin faster.
• Split ring commutator keeps it spinning one way.
• loudspeakers
• Changing current in coil.the force on coil.The cone moves and the sound is made.
• Electromagnetic induction
• if you have circuit flow you can make electromagnets. this electromagnet has a field.The field opposes the motion.The moving wire and magnet will produce a P.D
• Altenator
• produce a a.c current and uses slip rings
• Dynamo
• Produce ad.c current and uses split rings
• Transformers
• they change the size of the potential difference.
• they have two coils the primary and secondary.
• an Iron is a magnetic material and the core becomes magnetised and it will
• the changing magnetic field means that it will induce a p.d
• Step-up transformer and step-down transformer