P2P10 - Electrical circuits Flashcards
What is current?
The flow (movement) of electric charges.
The flow of electrons.
What is current measured in?
Amperes (A)
How do you calculate electrical current?
Current = Charge X Time
Whats an electrical insulator/conductor
A material that doesn’t/does allow current to pass through
Whats an example of electrical insulator?
PLastic/glass
Whats an example of electrical conductor?
Metals
Why can electrical conductors conduct electricity?
Because there are delocalised electrons
What is potential difference?
The difference in the amount of energy that charge carriers have between two points in a circuit.
What is PD measured in?
Volts (V)
How do we measure PD?
Using a Voltmeter
What is the PD of one volt?
The PD is equal to one Joule of energy being used by one Coulomb of charge when it flows between two points in a circuit.
What does an ammeter measure?
The flow of current that runs through it
What is resistance?
How difficult it is for current to flow through a component.
What is resistance measured in?
Ohms
What is the size of current affected by?
The resistance
The potential difference
Whats the equation for resistance?
Resistance =
Potential difference / Current
What happens if the wire in a circuit is longer?
The resistance increases
What is Ohms law?
Potential difference =
Currrent X resistance
How will stretching a wire affect its resistance?
Resistance will increase
What is a diode?
A component that only allows current to flow through it in one direction.
What is a Rectifier?
A component that turns an alternating current into a direct current.
What is a thermistor?
A thermistor is a component thats resistance changes with its temperature.
What effect will increased light intensity have on an LDR?
Decreased resistance
In a series circuit, what do resistors do?
Oppose the flow of electric current.
Increase resistance
What happens to the current when the wires split in a parallel circuit?
Splits equally throughout the 2 wire branches
What is voltage?
A measure of the difference in energy between one part of a circuit and another.
What is not split between 2 branches in a parallel circuit?
Voltage
In a parallel circuit what is the current through the energy source equal to?
The sum of the currents in the separate branches.
What colour stripes does the earth wire have and whats its potential?
Green and yellow
0V
What colour is the live wire and whats its potential?
Brown
230V
What colour is the neutral wire?
Blue
Whats the potential difference across the mains power supply in the UK?
230V
What is the National Grid?
The network of cables and transformers that connect power stations with houses and shops in the United Kingdom.
What are circuit breakers?
Special devices that switch off the flow of current if the current is higher than a certain value.
What are fuses?
Fuses contain a thin wire that melts if the current flowing through an appliance is too high.
What is an earth wire?
An earth wire is a low resistance wire that connects the metal case to the ground
Why is the live wire dangerous?
- Carries alot of electrical energy
- Might still hold potential difference when turned off
- High chance of shocking you
What is the unit for potential difference?
Volts
What is measured using Coulombs?
Charge
