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Physics - follow on task (MAGNETISM (Most materials are not magnetic, but…
Physics - follow on task
From looking at my magnets test, i could have done better on question 6 which required the knowledge on magnetism, electromagnets and magnetic fields so that is the topic/area i will be trying to work on.
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MAGNETIC FIELDS
What are magnetic fields?
-Region around a magnet that can affect magnetic materials.
-To see the magnetic field around a magnetic material, you can sprinkle iron fillings around the magnetic material resulting in the depiction of the magnetic charge lines of the magnetic field which will travel from the north pole to the south pole.
-The magnetic field is strongest at the poles however weakest away from the poles.
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MAGNETISM
Most materials are not magnetic, but some are. A magnetic material can be magnetised or will be attracted to a magnet. These metals are magnetic:
iron
cobalt
nickel
Steel is mostly iron, so steel is magnetic too.
A bar magnet is a permanent magnet. This means that its magnetism is there all the time and cannot be turned on or off. A bar magnet has two magnetic poles:
north pole (or north-seeking pole)
south pole (or south-seeking pole)
Attract and repel
If you bring two bar magnets together, there are two things that can happen, attraction and repulsion:
if you bring a north pole and a south pole together, they attract and the magnets stick together vice versa.
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Testing for magnets
How can you test if a piece of metal is actually a magnet? Seeing if it sticks to a magnet is not a good test, because magnetised iron, magnetic objects will also do this. So you can only show that an object is a magnet if it repulsion is shown.
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What makes iron magnetic?- Inside iron each atom acts as a small magnet (dipole). These are grouped together in domains. Domains in an unmagnetised piece of iron are arranged disorderly however when the iron is exposed to a magnetic field, the domains line up in the magnetic field.
Iron is a soft magnetic material therefore its easy to magnetise however iron loses magnetism very easily whereas steel is hard to magnetise but when magnetised, it keeps it so steel is a hard magnetic material.
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ELECTROMAGNETS
A Solenoid is a long coil of insulated wire which is used in many devices ( eg electromagnets) where a strong magnetic field needs to be produced
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An electromagnet is a solenoid in which the wire is wrapped around an iron core. When current is passed along a wire, a magnetic field is produced. Due to this the magnetic field magnetises the iron bar.
To strengthen the electromagnet you can, increase the current flowing through the coil, add more turns to the coil or wrap the coil around an iron core specifically.
The magnetic field around an electromagnet is just as similar as the one around a bar magnet. However it is possible for it to be reversed by turning the battery around. Unlike bar magnets (which are permanent magnet), the magnetism of electromagnets can be turned on and off just by closing or opening the switch.
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