- Water (solutions with electrolytes)
Graphite contains delocalised electrons (free electrons). These electrons can move through the graphite, carrying charge from place to place and allowing graphite to conduct electricity.
Pure water does not conduct electricity well. However, impurities, like salts, in the water turns it into a good conductor of electricity. When salts are dissolved in water, they separate into oppositely charged ions. These ions are mobile charge carriers (i.e. they carry charge and they can move freely in water). If a potential difference is applied, the positive and negative ions will start to move (in opposite directions), thus creating an electrical current.