Electricity Flashcards
symbol for bulb/lamp
a circle with a cross in it
symbol for battery
two vertical lines, the longer line represents a + and the shorter line represents a -
symbol for wire
line
symbol for a switch
two dots a line across it if the switch is on, the line lifted up represents that the switch is off
conductors
allow for the flow of electricity
insulators
minimise/don’t allow the flow of electricity
Does acrylic conduct electricity?
No
Does nickel conduct electricity?
Yes
Does lead conduct electricity?
Yes
Does bone conduct electricity?
No
Does carbon conduct electricity?
Yes
Does polystyrene electricity?
No
Does soft wood conduct electricity?
No
Does zinc conduct electricity?
Yes
Does steel conduct electricity?
Yes
The current in series circuit
The current in a series circuit has the same value at every point. The current does not et lost or used by the circuit.
Why does an open switch stop a current flowing?
This is because the circuit isn’t complete.
resistant increases as components added
current decreases as resistance increases
short circuit
A short circuit is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical independence. This result is in an excessive current flowing through the circuit. The opposite of a short circuit is an “open circuit”, which is an infinite resistance between two nodes.
If we use more batteries the current will be _____ so the bulbs will be _____. If we use more bulbs the current will be _____ so the bulbs will be _____. The extra bulbs cause more ______ in the circuit due to their thin wire _____. So there are ____ ways of changing the current in a circuit.
If we use more batteries the current will be greater so the bulbs will be brighter. If we use more bulbs the current will be lower so the bulbs will be dimmer. The extra bulbs cause more resistance in the circuit due to their thin wire filament. So there are many ways of changing the current in a circuit.
Are the bulbs in a parallel circuit brighter than bulbs in a series circuit?
Yes
Parallel circuit formula:
A1=A2+A3
current:
a measure of how many charges flow past at a certain time (rate of flow)
Bakery and supermarket analogy:
- empty vans collect bread at the bakery
- these vans are full of bread
- the vans deliver bread to the supermarket
- these vans are empty and go back to the bakery to collect more energy
- charges collect energy at the battery
- charges are atom sized particles already in the wire. The charges carry energy
- charges deliver energy to the bulb where it is transferred to heat and light
- charges return to the battery to collect more energy
charges:
atom sized particles in the wire
If there is one possible flow for a circuit then…
the charge will be the same anywhere on the circuit.
Colour of live wire
Brown
Colour of Earth wire
Green and yellow
Colour of neutral wire
Blue
Nerves
Electrical signal travel around our bodies along the nerves. Nerves are good conductors of electricity. The muscles contract not allowing you to let go of the electrical object.
What does the Earth wire do?
If the casing becomes live the Earth wire will redirect the electrical current down back to the plug which is a much faster route for it than going through a human and into the ground.
Fuse
A thin piece of wire which is thinner than the rest of the wire in the circuit. If the electric current gets too hot the fuse will melt and blow and this breaks the circuit do that the circuit is incomplete.
Where is the fuse put?
The live wire as it has the least resistance so there is a lot of current and it would be able to break the circuit if it becomes incomplete.
Hazards of mains supply:
- electric shock burns from contact with live parts
- injury from exposure to arcing, fire from faulty electrical equipment or installations
- explosion caused by unsuitable electrical apparatus or static electricity igniting flammable vapours or dusts
