Electricity and circuits T5 Flashcards
What is current?
The flow of electric charge around a circuit. Unit : ampere
What is the potential difference?
The potential difference (or voltage) is the driving force that pushes the charge around. Unit : volt. The potential difference is the energy transferred per coulomb of charge
What is resistance?
Resistance is anything that slows the flow down. Unit : ohm
What happens when there is a high potential difference?
There is a high current
What will happen if there is a high resistance?
There will be a low current
How do you work out charge?
Charge = current x time
What unit is charge in?
Coulombs
How do you work out energy transferred?
Energy transferred = charge moved x potential difference
How to work out resistance?
Resistance = potential difference / current
What does an ammeter do?
This measures the current (in amps) flowing through the component. It can be put anywhere in the main circuit
What does a volt meter do?
This measures the potential difference across the component. It must be placed under parallel with the component under test
What do linear components have on an iv graph?
A straight line
What do non - linear components have on an iv graph?
A curved line
How to work out the resistance on an iv graph?
The resistance will be the inverse of the gradient or 1/gradient. The steeper the graph the lower the resistance
What is an ldr?
An ldr ( light dependent resistor) is a resistor that is dependent on the intensity of light. In bright light, resistance falls. In darkness, the resistance is highest
What is a thermistor?
A thermistor is a temperature dependent resistor. In hot conditions, the resistance drops. In cool conditions, the resistance goes up
Which way do electric field lines travel?
Positive to negative