P2 - Electrical Circuits Flashcards
What is the meaning of electric current?
The rate of flow of electrons.
What is the meaning of potential difference?
The work done or the amount of energy transferred per coulomb of charge which passes between two points in a circuit.
What is resistance?
Something which opposes the flow of the current.
What does this symbol represent in a circuit?
Cell
What does this symbol represent in a circuit?
Battery
What does this symbol represent in a circuit?
Diode
What does this symbol represent in a circuit?
Fuse
What does this symbol represent in a circuit?
Light Dependent Resistor
Varies it’s resistance according to the light levels.
What does this symbol represent in a circuit?
Thermistor
Varies it’s resistance according to the temperature.
What does this symbol represent in a circuit?
LED
How does a thermistor work?
They can be used in applications such as fire alarms. They detect a difference in temperature. When the temperature is low there is a high resistance so little current can flow through them and then at high temperatures the resistance is much lower which allows more current to pass through.
How does an LDR work?
It can be used in applications such as security lights. When the light is bright there is low resistance and current can flow through it. When the light is dimmer there is a much higher resistance.
What component does this represent?
A resistor.
What component does this represent? Explain the graph.
A filament light bulb.
Resistance increases with temperature as the bulb warms up.
Electrons collide with ions in the wire.
Ions then gain energy.
The ions vibrate more.
There are then more collisions in the wire.
The resistance increases as it is harder for electrons to pass through.
What component does this graph represent?
Diode.
There is a very high resistance in one direction so that current cannot pass through.
