Which device is found within the secondary circuit of the x-ray system?

The x-ray tube is indeed found within the secondary circuit of the x-ray system. In radiography, the secondary circuit is responsible for the generation of x-rays and plays a crucial role in the production of the imaging process. The x-ray tube acts as the heart of this system; it is where the high-voltage electricity applied to the tube generates x-rays when electrons collide with the target material.

In the context of the function of the other components, the kilovoltage peak (kVp) meter is part of the control circuitry that monitors and regulates the voltage applied to the x-ray tube, but it is not part of the secondary circuit itself. The exposure timer controls the duration of the exposure but operates in coordination with the secondary circuit rather than being part of it. The milliamperage (mA) selector allows for the adjustment of the current to the tube but similarly does not reside within the secondary circuit. Thus, the significant function of converting electrical energy into x-ray production directly occurs within the x-ray tube, confirming its placement within the secondary circuit.