Voltage

When Colin goes through a power supply he picks up energy.

When Colin goes through a component like a bulb this energy is transferred into other forms, e.g. heat and light.

The amount of energy transferred per coulomb is called the voltage or potential difference (p.d.) across the component or power supply.

It is the difference in electrical potential energy before and after the component.  1 Volt = 1 Joule per Coulomb

Voltage (V) = Energy Transferred (J) / Charge (C)           V = W / Q

If there are several components in the circuit then the voltage from the power supply is shared between them. The ones that transfer the most energy have the largest voltage cross them.

Study these circuits carefully and try to understand how the voltage is distributed.