Now let us examine Chester's coffee can. The basic design of the coffee can dummy load is not altogether different from figure (D) above. The difference is that it is round, and that it has a rod connected to one end, such that we can move one of the plates. In this manner, we can change the distance between the capacitive plates, and hence, the capacitance within the tank circuit. By doing so, we can change the resonant frequency, and tune the cavity to have maximum resistance at a given frequency. The signal is applied at one end by a loop of wire, which transmits the signal into the cavity. If tuned properly, the cavity will present a very high resistance to the transmitter signal, and in essence, acts as a dummy load. The frequency at which it resonates is a direct result of the distance between the plates. From this we learn that the frequency of a resonant cavity is determined by its physical dimensions. The shape can be cylindrical, cubical, spherical, pyramid shaped, or otherwise, but the shape will also determine the circuits effective Q.