Current is the flow of __________. The amount of charge flowing through a component depends on its resistance. The __________ the resistance the __________ the current for a given potential difference across the component - current is __________ to resistance.
The resistance of a component can be found by measuring the current __________, and potential difference __________, the component. This is achieved using an ammeter in series with the component and a voltmeter in parallel with the component:
Resistance can then be calculated using 'Ohms Law' in which potential difference, current and resistance are related by the equation:
Potential difference (volt, V) = Current (ampere, A) × Resistance (ohm, Ω)
The resistance of a material is closely related to the number of charge carriers. Not only must the charge carrier have a charge, but they must also be able to move. In a metal the charge carrier is a delocalised electron. Metals with more delocalised electrons, have a __________ resistance - this is why different metals have different resistances.
There are special materials, in which the number of charge carries can change. This means they sometimes conduct electricity well, and sometimes they do not. These are known as semiconductors. Two such semiconductors are: