9. Choose the correct answer Idicate the formula for the attenuation of the X-ray flux in a substance: Phi =Phi _(0)/mu x Phi =Phi _(0)(-ln(mu x)) Phi =Phi _(0)mu x^-2 Phi =Phi _(0)e^-mu x

The correct answer is: $\Phi =\Phi _{0}e^{-\mu x}$<br /><br />Explanation: The attenuation of X-ray flux in a substance is described by the exponential attenuation law, which states that the intensity of the X-ray beam decreases exponentially with the thickness of the substance it passes through. The formula $\Phi =\Phi _{0}e^{-\mu x}$ represents this relationship, where $\Phi$ is the X-ray flux, $\Phi_{0}$ is the initial X-ray flux, $\mu$ is the attenuation coefficient of the substance, and $x$ is the thickness of the substance.