When the potential difference applied across an X-ray tube is...

The minimum wavelength of the emitted X-rays is given by \lambda_\min = \dfrac{hc}{eV}.

When the potential difference $V$ applied across the X-ray tube is increased, the minimum wavelength \lambda_\min decreases.

The total intensity of the continuous X-ray spectrum (total energy radiated per second) is proportional to the square of the accelerating voltage ($I \propto V^2$).

Therefore, when the potential difference is increased, the overall intensity of the emitted radiation also increases.