Electricity And Magnetism Flashcards
What is a material that easily allows an electric current?
An electrical conductor.
What is a material that does not allow electric current?
An electrical insulator.
Name some good electrical conductors.
Any metal, graphite (a form of carbon), salt water.
Name some materials that are electrical insulators.
Wood, plastic, and most non-metals.
What is the circuit symbol for a cell?
Draw the circuit symbol for a cell.
What is the circuit symbol for a battery?
Draw the circuit symbol for a battery.
What is the circuit symbol for a bulk?
Draw the circuit symbol for a bulk.
What is the circuit symbol for a solenoid?
Draw the circuit symbol for a solenoid.
What is the circuit symbol for a variable resistor?
Draw the circuit symbol for a variable resistor.
What instrument is used to measure current?
An ammeter.
What does an ammeter measure?
Current.
What is the unit of current and what is its symbol?
Amperes, A.
What happens if I increase the number of cells in my battery?
The current will increase.
What happens when the charge moves through the cell?
It gains energy.
What is the unit of potential?
Volt, V.
What happens if I connect more bulbs in series?
The 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.
What is the important rule to remember at a junction in a circuit?
Total current in = total current out.
What poles of a magnet attract each other?
The opposite poles (North and South).
What happens when like poles of magnets come together?
They repel.
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?
Using magnetic field lines.
How could you visualize the field around a magnet?
Using iron filings or a compass.
What is the shape of a magnetic field around a wire?
Circular.
How can we tell the direction of the magnetic field lines around a wire?
Using the right-hand ‘thumbs up’ rule: Thumb points in the direction of the current, fingers show the direction of the field lines.
What is the effect of current flowing in a wire?
It creates a magnetic field.
Draw the magnetic field around a solenoid.
Draw the magnetic field around a 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 (this protects the user from high currents).
List some uses of electromagnets.
In relays (e.g. to switch off floodlights or x-ray machines in hospitals), in scrapyards to move parts, maglev trains, in electric motors, in rollercoaster braking.
