Controlling And Using Electic Current Flashcards
What is voltage
The electrical pressure that pushes the current around the circuit
What is the resistance
Anything in the circuit that slows the current
What happens when you increase voltage
More current will flow
What happens when you increase resistance
Less current will flow
How does an ammeter work
It measures the current through the component
They work in series with the component
How does the voltmeter work
It measures the potential difference across the component
It must be in parallel with the component
What happens in fixed resistors
The current through a resistor is proportional to voltage
What happens in a filament lamp
As the temperature of the Filipe the increases the resistance increases causing a curve
What happens in a diode
Current only flows through in one direction causing the graph to only curve up after 0
Potential difference =
Current X resistance
Or
V = I x V
What does a light dependent resistor do
It changes its resistance depending on how much light there is
In bright light there is less resistance
In a dark light the resistance is highest
What does a thermistor do
It’s resistance depends on the temperature
When hot the resistance falls
When cold the resistance is highest
Why do resistors get hot
When there is an electric current in a resistor there is energy transfer due to the electrons colliding with ions in the lattice that make up the resistor
These collisions give the ions extra energy which is emitted as heat
The heat increases the resistance so less current will flow
Why is it bad when resistors get hot
They can melt components
It makes the circuit less efficient
Electrical power =
Potential difference X current
P=VxI
