Current and Voltage Flashcards
When does a current flow?
When an electric charge moves around the circuit.
What is current measured in?
Amperes, amps
How is current measured?
Using an ammeter.
Why is a voltage needed?
To make a current flow through it.
What is voltage measured in?
Volts
How is voltage measured?
Using a voltmeter.
When does an electric current flow?
When electrons move through a conductor.
What happens when moving electrons collide with atoms of the conductor?
It makes it difficult for the current to flow and causes resistance.
When are electrons more likely to collide with atoms from the conductor?
A long wire rather than a short wire.
A thin wire has fewer electrons to carry the current than a thick wire. What does this mean?
The resistance in a wire increases.
The length of the wire increases.
The thickness of the wire decreases.
What are thermistors?
Temperature sensors.
Explain thermistors.
At low temperatures, the resistance of a thermistor is high, and little current can flow through them.
At high temperatures, the resistance of a thermistor is low, and more current can flow through them.
What are LDR’s? (Light-dependent resistors)
Light level detectors.
Explain LDRs.
In the dark and at low light levels, the resistance of an LDR is high, and little current can flow through it.
In bright light, the resistance of an LDR is low, and more current can flow through it.
