Electromagnetism Flashcards
The magnetic field changes if
The conducted goes into/out of a magnetic field
Magnet moves towards/away from the conductor
Magnetic field is being varied
How to increase the electromagnetism
Increase current through coil Increase the number of turns on coil Wind the coil around a magnetic material Use a soft material Core must magnetise easily But demagnetise when no current
Transformer
A core of magnetically soft material
To change voltage with very little power loss
Input voltage stepped down if
N1>N2
Input voltage stepped up if
N2>N1
Generating electricity with nuclear fission
a chain reaction
Energy is released slowly
Heat produced used to generate steam
Steam can turn turbines and generators
Graphite moderator
Absorbs some energy of fast neutrons
Boron control rods
Absorbs neutrons to completely take them out of action
Can be controlled to speed up or shut down a reaction
Advantages of electromagnets
Can change the strength
You can turn theme on and off
Don’t break if you drop them
How is current generated in a coil of wire
The coil is moved through a magnetic field l
Disadvantages of electromagnets
Require electricity
Expensive
Electricity pollutes
More complicated than fixing magnets
Structure of a transformer
Soft iron core
Primary, secondary coil
Magnetic materials
Iron
Steel
Cobalt
Nickel
Flemings ruler
Left hand
Thumb: motion
Index: field
Bent central finger: current
How can voltage and current be increased
More coils
Stronger magnet
Faster movement
