ProPie · FreeFirst 4 topics of every subject
Current, voltage and resistance
- Current (I) is the rate of flow of charge: I = Q ÷ t, measured in amperes (A).
- Potential difference (V) is the energy transferred per unit charge, measured in volts (V).
- Resistance (R) is V ÷ I, measured in ohms (Ω). For an ohmic conductor it stays constant if the temperature does.
- Series and parallel: in series the current is the same everywhere and voltages add; in parallel each branch has the same voltage and currents add.