Electricity And Magnestism Flashcards
Atoms
Everything us made of particles called atoms. Their charge is neutral.
What are atoms made of.
Protons - positive charge
Electrons - negative charge
Neutrons - no charge
Attraction and repelling
Like charges repel and unlike charges attract.
Static electricity
When two objects are rubbed together, electrons are transferred from one object to another.
Current electricity
From the flow of electrons along a conductor.
Electric field
Is a region where there is a force on charged particles or materials.
Electric current
It is the amount of charge flowing per second. You measure it in amps (A) with an ammeter.
Potential difference
The potential difference of a cell (battery) tells you the size of the push on the charges and how much energy can be transferred by them.
How do you measure potential difference.
It is measured in volts (V) using a voltmeter. The rating of a cell or battery tells you the potential difference at which it operates..
What is a series circuit?
It contains only one loop and the current is the same everwhere.
What is a parallel circuit?
A parallel circuit has multiple branches and the current in the branches add up to make the total current.
Potential difference - series circuit
The potential difference across each component adds up to the potential difference across the battery.
Potential difference - parallel circuit
The potential difference across each component is the same as the potential difference across the battery.
Resistance
A component with a hugh resistance has a small current running thorugh it.
Insulator
Has a high resistance to current eg plastics
Conductor
Conductors have a low resistance to current eg metals.
How do you calculate resistance.
Resistance is measured in ohms.
You calculate resistance = potential difference (voltage) \current (A)
What do magnets have?
They have a north and south pole.
Like poles repel and unlike poles attract.
What are the 4 magnetic materials?
Iron, cobalt, nickel and steel.
Magnetic field
Magnetic materials feel a force in the region around a magnet called a magnetic material.
Magnetic field lines show the pattern of a magnetic field. They run from the north pole to south pole.
How do you find magnetic field lines?
You can see the field with a small compass or iron filings.
If the lines are closer together the field is stronger.
What is an electromagnet?
A current flowing in a coil of wire wrapped around a magnetic material is an electromagnet. They are only magnetic when they have a flow of current, so they can be turned on and off.
Electromagnets have what in their centre?
They usually have an iron core in the middle which makes them stronger.
How do I make an electromagnet stronger?
Adding more loops/turns in the coil.
Using more current.
The type of core.
You can make electromagnets much stronger than permanent magnets.
What are the uses of electromagnets?
Moving cars or other metal objects (scrap yard)
Sorting iron and steel from aluminium.
Making motors and speakers.
Making levitating trains, which travel much faster as there is no friction.
How do motors work?
Applying a current to a coil of wire makes it electromagnetic.
This causes a force between the coil of wire and the permanent magnet nearby, driving a motor.
