Creating a timer in an RC circuit
You connect the buzzer in parallel with C.

The problem is that most buzzers will conduct some current as C is charging up and this will affect your timing. I think you have to assume one of two things from the vagueness of the question and both give the same result.







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1.


Figure 1a has a "magic buzzer" which doesn't load C until 2/3 supply is reached. It then buzzes. It may buzz until C discharges to some lower voltage. Alternatively, it may be have a low enough current that R is able to power it indefinitely so that Vc remains constant or even increases slowly.
Figure 1b has a buzzer with some active electronics. It is powered from the supply and when the threshold exceeds a preset level the buzzer will sound. The threshold input could be made very high impedance so it wouldn't load the capacitor significantly.


The question is a little unfair. The non-thinker might be able to answer it straight-away whereas the thinker could get caught in the details.