electricity and magnetism Flashcards
permenant magnet
steel
magnetic material
iron
how to induce magnetism
a nail is made into a permenant magnet by its closeness to a permenant magnet
demagnetisation of magnet simple
heat it or hit it with a hammer
what is a magnetic field
a region where a magnetic pole experiences a force
what is the only test for a magnet
repulsion
how to make a permenant magnet ( complex)
place steel rod inside coil, use high dc current, leave steel inside, turn of current
how to change the strength of an electromagnet
increase current
use iron core
more turn in wire
examples of electromagnets
electric bells
loudspeakers
charging negative rod by friction
both cloth and rod contain equal number of protons and electrons
rub plastic polythene ( white) rod with cloth, electrons move from cloth to rod
rod becomes negative
charging a positive rod by friction
both contain equal number of protons and electrons
rub acetate clear plastic rod move from rod to cloth
non-metals can be charged by friction
electric field
region where electric charge experiences a force
the greater the number of lines per unit area, the greater the strength of the electric field
electric fields directions diagram
+ = arrows away
- = arrows towards
+ - = charge goes from positive to negative
2 plates= from positive to negative
current formula
charge/ time
examples of conducters
- metals, because they have free electrons
- carbons is a conducter