What results from large potential differences across an X-ray tube?

In an X-ray tube, a significant potential difference (or voltage) between the anode and cathode is crucial for the production of X-rays. The high voltage accelerates electrons emitted from the cathode towards the anode. When these high-energy electrons collide with the metal target (anode), they can transfer enough energy to the atoms of the target material to produce X-rays.

The term "hard X-rays" refers to X-rays that have high frequencies and correspondingly high energy. These X-rays are typically produced when the potential difference is sufficiently large, as the accelerated electrons possess enough kinetic energy upon impact to produce these high-energy photons. Therefore, a large potential difference increases the likelihood of producing hard X-rays due to the high energy of the electrons generated.

This understanding distinguishes hard X-rays from softer X-rays, which would be produced at lower energy and lower potential differences. The relationship between electron acceleration and the energy of the resulting X-rays is key in understanding X-ray production in such tubes. Hence, the generation of hard X-rays with high frequencies is directly linked to the application of large potential differences across the X-ray tube.