Electricity and Magnetism Flashcards
A material which easily allows an electric current is
an electrical conductor
A material which does not allow an electric current is
an electrical insulator
Name some good electrical conductors
Any metal (some are better than others!), graphite (a form of carbon)
Name some good electrical insulators
Wood, plastic (most non-metals in fact)
What instrument is used to measure current?
Ammeter
What does an ammeter measure?
Current
What is the unit of current and what is its symbol?
Amperes, A
If I increase the number of cells in my battery the current will…?
Increase
When the charge moves through the cell it gains…?
energy
Energy per unit charge is also known as….
potential
What is the unit of potential?
volt, v
If I connect more bulbs in series with each other the resistance will… and the current will…?
Resistance will increase and the current will decrease
What is the unit of resistance?
ohm, Ω
What is current?
The amount of charge passing a point each second
At a junction in a circuit what is the important rule to remember?
total current in = total current out
Which poles of a magnet attract each other?
The opposite poles (North and South)
What happens when like poles of magnets come together?
They repel
What happens when more bulbs are connected in series?
The resistance will increase and the current will decrease.
Give some examples of magnetic materials.
Iron, Steel, Cobalt, Nickel.
Give some examples of non-magnetic materials.
Plastic, Wood, Paper, Rubber, Glass.
Why does the Earth have a magnetic field?
The core of the earth is a rotating ball of Iron.
What is a magnetic field?
The region around a magnet where other magnetic materials experience a force.
How are magnetic fields represented in diagrams?
Magnetic field lines.
How could you visualize the field around a magnet?
Using iron filings, or using a compass.
What is the shape of a magnetic field around a wire?
Circular.
How can we tell the direction of the magnetic field around a wire?
Right hand ‘thumbs up’ rule. Thumb points in the direction of the current.
What do we call the effect when a current flows in a wire and generates a magnetic field?
Electromagnetism.
How do you draw the magnetic field around a coil/solenoid?
Draw the magnetic field lines around the solenoid.
Name 3 ways to increase the strength of the magnetic field around a solenoid.
Increase the current, increase the number of turns on the coil, add an iron core.
What is one of the major advantages of an electromagnet compared to a permanent magnet?
Electromagnets can be switched on and off.
What is a relay circuit used for?
To activate high voltage circuits using low voltage circuits.
Give some uses of electromagnets.
In relays (e.g. to switch off floodlights or x-ray machines in hospitals).
