Magnetism-Paper 2
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What is a permanent magnet
A magnet which as a north pole and south pole and produces its own magnetic field
What is a magnetic field
The region around a magnet where a force acts on another magnet or on a magnetic material
How are permanent magnets and induced magnets different
A permanent magnet produces its own magnetic field An induced magnet is a material that becomes a magnet when placed in a magnetic field
What is produced when you have a current carrying wire
Produces a magnetic field
What is a solenoid
A coil of wire The magnetic field inside a solenoid is strong and uniform
What is an electromagnet
A solenoid with an iron core
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Describe how an electromagnet can be made from a solenoid
Connect solenoid to a power supply The current produces a magnetic field Place iron in middle to increase field strength Iron core becomes an induced magnet
How is an electromagnet more advantageous than a permanent magnet
An electromagnet’s magnetic field can appear and disappear Magnetic field can be turned on and off
What is the motor effect
When a current wire (which produces a magnetic field) is put within another magnetic field Two magnetic fields interact Causes the magnet and the wire to exert a force on each other
How is rotation caused in an electric motor
A coil of wire has current flowing through it The current produces a magnetic field around the wire Wire is placed in a magnetic field. Exert forces on each other Coil spins as the forces act on either side
What is the generator effect
If an electrical conductor moves relative to a magnetic field OR if there is a change in the magnetic field around a conductor A potential difference is induced across the ends of the conductor
How does an induced current oppose the change that made it
An induced current generates a magnetic field that opposes original change
What are Alternators
Generate alternating current Rotate a coil in a magnetic field and so cut the magnetic field lines which induces a PD across the coil
What are Dynamos
Generate direct current Same as alternating current but split-ring commutator instead of slip rings
What is the direction of the induced current in the generator effect
Produce a magnetic field that opposes the change causes the current
Describe what transformers do
An AC current occurs in the primary coil Produces a magnetic field in the iron core Magnetic field induces an alternating PD Secondary coil=AC induced current will flow through