Magnetism
Number of poles of a magnet
Two (2)
How to make an electromagnet
Run electricity/current through a conductor/coil
Change direction of Lorentz force
Change direction of magnetic field, change direction of current
True or false: Current is produced when a conductor is placed in a changing magnetic field
True
Transformer can only be used with this type of current
Like poles near each other will do this
Repel
Strength of electromagnet will increase
2 ways to increase the magnitude of current produced by bicycle dynamo
Stronger magnetic field, faster speed, more turns in the coil
What kind of transformer: Vin > Vout
Step down transformer
Direction of magnetic field lines
North to South
How to change polarity of electromagnet
Energy conversion in a bicycle dynamo
Kinetic energy to electricity
Increases transformer efficiency by reducing eddy currents
Earth's magnetic field is used by both human and animals for this
Navigation/finding direction
What kind of hand rule is used to determine polarity of electromagnet?
Right hand grip rule
Hand rule to determine direction of Lorentz force
Fleming's Left hand rule
2 example of important use of the principle
transformer, generator, dynamo (any 2)
What kind of transformer:
Number of turns in primary coil < Number of turns in secondary coil
Step up transformer
The Earth's magnetic field protects us from ....
Dangerous gases & charged particles
1 example of application of STRONG electromagnet
Maglev/MRI/generator
Definition
Force on a conductor when a current flows through it in the presence of magnetic field
First discovered by ...
Michael Farraday
Cause for power loss (aka reduced efficiency) in a transformer
Power lost as heat due to resistance of wire, eddy currents