P3.2.4 - Graphs Of p.d. And Current Flashcards
What is a characteristic graph?
A graph of current against potential difference
How do you collect data for a characteristic graph?
You take measurements of the current flowing through the components for different potential differences, and then reverse the power supply and note down the new measurements
What do you do once you have collected your measurements for your characteristic graph?
You calculate the resistance and then plot the characteristic graph with potential difference in the x-axis
What do you need in a circuit for the resistance to be linear?
A resistance wire or resistor
If a characteristic graph gradient is straight, what does this mean?
The resistance is linear, the wire is a linear circuit element
When did George Ohm discover that wires were linear elements?
1827
What is Ohm’s Law?
Current is proportional to potential difference if the temperature does not change
If a characteristic graph is not linear, what does this show?
The temperature has affected the resistance
Why does temperature affect resistance?
The current increases because the hot wire causes the ions to vibrate more which allows the electrons to travel quicker which increases the current quicker than the potential difference
What is a diode?
A component that only allows a current to flow a certain direction
Describe the characteristic graph of a diode.
The potential difference increases, but the current does not change. Then, suddenly the charge increases very quickly compared to the potential difference
