I can't answer Q3 of: A spin-drier has a start-stop switch, but the motor will only spin the drum if the lid is closed. Closing the lid closes an SPST switch inside the machine, and the motor can then be started with the start-stop switch. 2) Draw a diagram of a simple circuit for this (done - with battery, SPST, push switch and motor in series) 3) Add a buzzer to your circuit diagram so that the buzzer will sound if the lid is not closed and the start-stop switch is operated (remember that a buzzer requires much less current than a motor does). I cannot work out Q3. If I add a cell and buzzer in parallel with the push switch it would sound when the lid is open and when the lid is closed so this wouldn't work. Any help would be much appreciated!