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p4 (magnetic forces (when a current carrying conductor eg wire is puts…
p4
magnetic forces
when a current carrying conductor eg wire is puts between magnetic poles the two fields affect on another, results in force on the wire
to experience full force, wire at 90 degrees to mag field, if wire runs along it, no force at all, at angles in between some force felt
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force acts in same direction relative to the magnetic field of magnets and direction of current in the wire, changing either changes direction of force
apply current to set of rails inside horse shoe magnet, bar set on rails, generates force that rolls bar along rails
fleming's left hand rule, First in direction of mag Field, seCond in current, thuMb shows force (Motion)
magnets
have two poles, north and south
magnetic field is where a magnetic material (iron, nickel or cobalt) experiences a force
magnetic field lines show the size and direction of magnetic fields, always point from north to south
closer field lines are to each other, the stronger the magnetic field at that point
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magnetic field patterns
put magnet under paper and scatter iron filings on top, will align themselves with the field lines
put magnet on paper, place compass on paper next to magnet, needle points in direction of field line at this position, mark two dots at each end of needle, move and repeat, join up for a field line
compass is better than iron filings as the drawing of the field is still there after the compass is gone, and shows direction of field lines
iron filings hard to work with, hard to collect if dropped, hard to take off a magnet if they get in contact
compasses always point north if not near a magnet, shows the earth has a magnetic north and south poles and therefore a magnetic core
effect
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magnetism induced by the original magnet, closer they get, the stronger the induced magnetism
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solenoid
lots of coils of wire join to make a solenoid, increases magnetic effect, field inside a current carrying solenoid is strong and uniform
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magnetic effect increases if current is increased, number of coils increased but length stays same, cross sectional area of solenoid decreases, length decreased but turns stays same, iron core added inside
electromagnetism
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larger the electric current, the stronger the magnetic field
magnetic field around a straight current carrying wire made of concentric circles with wire in center, direction of the field with right hand rule
around a flat circular coil : magnetic field in the center of a flat circular coil of wire is similar to a bar magnet's
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