For obvious reasons you do not want to switch a washing machine on until the door is closed, and though the machine is plugged into the power supply which is always switched on, you do not want the machine to turn on until you turn the on dial. To achieve these twin aims we can use an AND logic gate.
Typically too – to save energy for example – you will not want the machine to be switched on until water has reached a level such that the clothes will be washed when the machine starts to turn. We can achieve this by adding another AND gate as shown below.
