Penetrating power of $X$-rays increases with an increase in

$A$ charged gold leaf electroscope has its leaves apart by a certain amount with enclosed air. When the electroscope is subjected to $X$-rays,then the leaves

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 minimum wavelength of $X$-rays emitted by an $X$-ray tube is $0.4125 \mathring{A}$. The accelerating voltage is ...... $kV$.

The range of wavelength for $X$-rays is from . . . . . . .

When $0.50\; \mathring{A}$ $X$-rays strike a material,the photoelectrons from the $K$-shell are observed to move in a circle of radius $23\; mm$ in a magnetic field of $2 \times 10^{-2}\; T$ acting perpendicularly to the direction of emission of photoelectrons. The binding energy of $K$-shell electrons is $..........\; keV$.