Circuits Flashcards
How is static electricity achieved?
By rubbing certain insulating materials together, transferring electrons from one to the other, which leaves a positive static charge on one and a negative static charge on the other
-e.g. polythene rod and duster, balloon and jumper
Which charges repel and which attract?
- Like charges repel
- Opposite charges attract
What can charges move easily through?
Conductors
What is current?
Flow of electrical charge around a circuit
When does current only flow?
When there is potential difference
What is potential difference?
Driving force that pushes current round the circuit (work done per unit of charge)
What is resistance?
Anything in the circuit which slows the flow down
What effect does temperature have on resistance?
It increases with temperature as heat causes ions to vibrate more so they get in the way of the electrons more making it harder for current to flow
Why do resistors have a limit of current that can flow through?
Becasuse an increase in current increases temperature, which increases resistance, so current decreases again
How must an ammeter and voltmeter be connected to a circuit?
- Ammeter must be connected in series
- Voltmeter must be connected in parallel
What is a diode, what is it made from, and what is it used for?
- Only allows current to flow in one direction
- Made from a semiconductor such as silicon
- Used to regulate potential difference
What is a light-emitting diode and what is it used for?
- Emits light when current flows through in the forward direction
- Used to show an appliance is switched on
Why is a light-emitting diode (LED) better than other forms of lighting and where is it being used?
-Uses smaller current so is being used more in traffic lights, remote controls and digital clocks
What is a light-dependent resistor and where is it used?
- Resistor dependent on intensity of light
- As light intensity increases, resistance decreases
- Used in streetlights and burglar detectors
What is a thermistor and where is it used?
- Resistor dependent on temperature
- As temperature increases, resistance decreases
- Used in temperature detectors e.g. thermostats
What is a series circuit and where are they used?
- Components connected in a line (except voltmeter)
- e.g. fairy lights
What happens if one component is removed from a series circuit?
The circuit is broken and all components stop
What happens to potential difference in a series circuit?
Potential difference is shared and equals source voltage
What happens to current in a series circuit?
Current is the same everywhere in the circuit
What happens to resistance in a series circuit?
Total resistance is the sum of all resistance in the circuit
What is a parallel circuit and where are they used?
- Each component is separately connected to the supply
- e.g. everything electrical in a car
What happens if one component is removed from a parallel circuit?
Removing one component hardly affects the others
What happens to potential difference in a parallel circuit?
Potential difference is the same across all branches; they all get the full source voltage
What happens to current in a parallel circuit?
Current is shared between the branches and equals total current. It splits and rejoins at junctions
