Ohm's Law
In a simple circuit, the current through a conductor is proportional to the voltage across it. The constant that links them is the conductor's resistance.
Worked example. A 12 V battery drives a 4 Ω resistor. Current: I = V / R = 12 / 4 = 3 A.
Notes to write down
- Ohm's Law: V = I × R (voltage = current × resistance)
- Units: current I in amperes (A), voltage V in volts (V), resistance R in ohms (Ω)
- Rearrange: I = V / R and R = V / I
- Higher resistance → less current for the same voltage