Modelling is used to show how the current and charge in a circuit is not used up even though the energy store in a battery reduces over time. The presenter explains that a battery is a store of energy which can provide the 'push' or potential difference to get current flowing. In the model we see current and charge flowing in a complete circuit to light the bulb. The bulb uses energy to shine but does not use the current up. This is demonstrated in a model using water instead of current. Over time the energy from the battery is used up by the bulb.
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