Ohm's Law
- Ohm's Law states that:
The current through a conductor is directly proportional to the potential difference across it
- Electrical conductors that obey Ohm's Law are referred to as ohmic conductors
- Examples of ohmic conductors are:
- Fixed resistors
- Wires
- Heating elements
- Ohm's Law is represented by the equation V = IR
- If V and I are directly proportional, this means that the resistance R remains constant
- Ohm's Law is relevant only at constant temperatures
- An ohmic conductor will have a current-voltage (I–V) graph that is a straight line through the origin
An I-V graph for an ohmic conductor is a straight line graph through the origin
- Reversing the potential difference (and direction of the current) makes no difference to the shape of the line, the potential difference and current values will just be negative
- If the axis labels are swapped around (the current on the x-axis and p.d on the y-axis) the graph will still be a straight line through the origin