P2 - Electricty Flashcards
What is current? Amps
Flow of electrical charge
What is potential difference? Volts
Driving force that pushes charge round
What is resistance? Ohms
Anything that slows down charge flow
Why does current through a component depend of the components resistance?
The greater the resistance, the smaller the current.
Why does current through a component depend on the potential difference across the component?
The greater the potential difference, the larger the current.
What are the three things in a series circuit?
- Current is the same everywhere
- Total source potential difference is shared between components.
- Total resistance of components is the sun if their resistance.
What is the difference in adding a resistor in a series circuit and a parallel circuit?
Series = increases the total resistance of the circuit
Parallel = decreases the total resistance of the circuit
What is an alternating current?
Current that constantly changes direction and is produced by an alternating voltage. Used in mains supply.
What is a direct current?
Current that always flows in the same direction and is produced by a direct voltage. Supplied by batteries.
What are 3 facts about UK Mains?
- AC supply
- Frequency of 50Hz
- Voltage around 230V
What are the three - core cables called and what are their colours?
- Live wire - brown
- Neutral wire - blue
- Earth wire - green and yellow
What is the potential difference of all the wires?
Live - 230V
Neutral - around 0
Earth - 0
What are the uses of the three - core cables?
Live - provides alternating PD from mains supply.
Neutral - completes the circuit.
Earth - stops appliance casing becoming live.
How does an electric shock work?
Large PD produced across body when touching a 230V electric supply.
Current flows through body.
What is the National Grid?
A system of cables and transformers that connect power stations to consumers.
What is a step - up transformer and step - down transformer?
Step - up = increase Pd
Step - down = decrease Pd
How does static electricity work? (4)
- Rub two insulating materials together
- Electrons move from one to the other
- Both materials become electrically charged. Charge on each material is equal and opposite.
- Only electrons move, positive changes don’t move
