26年8月国际D卷练习 · 第 16 题

The function \( f\left(x\right)\ =\ 900\left(0.5\right)^{\frac{x}{12}} \) gives the predicted intensity of a beam \( f\left(x\right)\ \) , in number of photons in the beam,  \( x\ \) millimeters below the surface of a certain material. What is the best interpretation of \( f\left(12\right)=450\ \) ?