Electricity and magnetism Flashcards
What is induced magnetism
An unmagnetised object gains temporary magnetic capabilities when put in a magnetic field
Magnetic properties of soft iron
- Easy to magnetise
- Easy to demagnetise
- Ex) Electronic door locks
Magnetic properties of hard iron
- Hard to magnetise
- Hard to demagnetise
- Ex) devices needed constant magnetic fields
What are electromagnets
A magnet caused by the flow of current in a coil
Properties of electromagnets
- Variable strength magnetic field
- Can switch on and off quickly
- North and south pole can be changed by changing direction of current
- Ex) Electric door locks, MRI machines
Properties of permanent magnet
- Constant magnetic field
- Cannot be turned off or on
- North and south cant be changed
- Ex) Speakers
Methods of magnetism
- Stroking with a magnet
- Use a d.c. in a coil
- Hammering in a magnetic field
What kind of electric charge
Positive and Negative
What does charging a body do
Addition or removal of electrons
What is an electric field
Region in which an electric charge experiences a force
What are electrical conductors
Materials in which current can flow
Ex) Copper, aluminum, gold and silver
What are electrical insulators
Materials that cannot conduct electricity
Ex) Glass, wood, paper, air, and rubber
Define current
the rate at which electrons flow past a point in a complete electrical circuit
Define potential difference
the difference in the amount of energy that charge carriers have between two points in a circuit
Define e.m.f
Electromotive force - measures how much push it can provide and how much energy it can transfer
