Fill in the Blanks 1SBO/1SRO Direct current and alternating current textOnline version Here you can practice the vocabulary from unit 2.7.1. by Cristina Hernández Alcaine 1 The current from a cell is , a constant flow of electricity which travels around a circuit in one direction . The electricity supplied to homes and other buildings , called , is current . Unlike DC supply , an AC supply flows backwards and forwards ( its direction continually alternates ) . The rate at which the current alternates , called the , is measured in . For example , in the UK , AC supply is 50 Hz , it alternates 50 times per second . On a graph , the AC supply of mains electricity forms a sine wave . The current supplied to most homes is - , it forms one single wave . In factories and large buildings , which have powerful electrical equipment , the supply is often - , effectively three currents , each with a different phase ( timing ) . This provides a smoother supply as it reduces the gaps between the voltage peaks .
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