2bMains electricity

Syllabus objectives

• 2.2understand how the use of insulation, double insulation, earthing, fuses and circuit breakers protects the device or user in a range of domestic appliances
• 2.3understand why a current in a resistor results in the electrical transfer of energy and an increase in temperature, and how this can be used in a variety of domestic contexts
• 2.4know and use the relationship between power, current and voltage: power = current × voltage P = I × V and apply the relationship to the selection of appropriate fuses
• 2.5use the relationship between energy transferred, current, voltage and time: energy transferred = current × voltage × time E = I × V x t
• 2.6know the difference between mains electricity being alternating current (a.c.) and direct current (d.c.) being supplied by a cell or battery