Electricity Flashcards
Insulator
A material that can’t conduct electricity as electrons can’t flow through them.
Static electricity
When 2 insulators rub against each other, the electrons from one insulator transfers to the other, making it positive and the one that gained electrons negative. The size of this charge is equal making the 2 insulators repel each other.
How does a van de graaf generator work?
Electrons are transferred from the plastic roller, to the belt then the floor.
The top becomes positive and the dome stores it.
When dome is touched, hair strands become positively charged and therefore repel each other.
When do static shocks occur?
When a river of electrons discharges from you and flows through the air, normally when touching a conductor.
What is the blue wire in a plug?
Neutral wire - completes the circuit. 0V
bLue goes Left in the plug
What is the brown wire in a plug?
Live wire - contains the current. 230V.
bRown goes Right.
What is the yellow and green wire in a plug?
Earth wire - connects to the case wire so if a live wire becomes live it directs it to the ground to prevent a shock.
0V.
sTriped goes to the Top.
What does the fuse do in a plug?
If too much current passes through, it can damage the circuit. The fuse melts to cut off the live wire to prevent damage.
What is the Mains electricity?
What generates electricity in the UK for shops, houses, offices and factories.
Voltage in the mains?
At 230V with an alternating current (changes direction) of 50Hz.
What is the national grid?
A series of pylons and cables that connects power stations (mains electricity) to offices, houses, shops etc.
What do step up transformers do?
Increases voltage so it can travel to buildings from the power station quicker. Also decreases current so the wires don’t heat up as much.
What do step down transformers do?
Decreases voltage so it’s safe for home use and increases current.
Why are cables thick in the national grid?
To decrease resistance.
How to find the power using resistance and current?
Power = current² x resistance
P = I² x room
(Pig In a Square Room)
Why is the national grid efficient?
With a high potential difference, less current is needed to deliver the same amount of power.
Why is the national grid efficient?
With a high potential difference, less current is needed to deliver the same amount of power.
What are wires made of in appliances?
Copper, a good conductor of electricity.
What is the outer plug made of?
Plastic, as it’s a good insulator and you won’t get a shock if you touch it.
Why do cables have thicker wire than for lighting?
More current passes through wall cables, so they need a thicker wire for less resistance
Why do cables have thicker wire than for lighting?
More current passes through wall cables, so they need a thicker wire for less resistance. This also stops the heating effect of a high current.
What is power?
The energy transferred per unit of time.
How to find the power using current and voltage?
Power = current x potential difference
P = I x V
(Penguins In Vegas)
How to find the energy transferred using power and time?
Energy = Power x Time
E = P x T
(Eat Pie Today)
Electric field
The area surrounding an electric charge that will have an influence on other charged particles, even if its not touching
Arrows on field lines on an electric field
Show the effect if a positive object is brought nearby
If the particle is negative, the arrows will point inwards as a positive object is attracted to the opposite charge
If the particle is positive, the arrows will point outwards as a positive object is repelled from the same charge
Distance and field lines
The closer to the particle, the stronger the force
The further away on the field lines, the weaker the force
