For harder $X$-rays:

After passing through a gold film of thickness $5 \times 10^{-3} \ m$,the intensity of an $X$-ray beam decreases to $36.8\%$ of its initial intensity. The absorption coefficient is ....... $m^{-1}$.

The wavelength of the $K_\alpha$ line for an element of atomic number $Z_1 = 29$ is $\lambda$. What is the wavelength of the $K_\alpha$ line for an element of atomic number $Z_2 = 15$? (Take Moseley's constant $b = 1$ for both elements.)

An $X$-ray tube is operated at $1.24$ million volts. The shortest wavelength of the produced photon will be ..... $nm$.

When cathode rays strike a metal target with a high melting point and high atomic number,what is produced?

If the $K_\alpha$ radiation of $Mo (Z=42)$ has a wavelength of $0.71 \;\mathring A$,calculate the wavelength of the corresponding $K_\alpha$ radiation of $Cu (Z=29)$ (in $\mathring A$). (in $.52$)