The distance between interatomic lattice planes is $10\ \mathring A$. The maximum wavelength of $X$-rays that can be diffracted by this crystal is ......$\mathring A$.

The energy of a photon of characteristic $X-$ rays from a Coolidge tube comes from

The wavelength of $X-$rays is of the order of

The structure of solids is investigated by using

The potential difference applied to an $X$-ray tube is $5 \ KV$ and the current through it is $6.4 \ mA$. The number of electrons striking the target per second is:

$X$-rays of wavelength $0.1 \ \mathring A$ are allowed to fall on a metal and get scattered. The wavelength of the scattered radiation is $0.111 \ \mathring A$. If $h = 6.624 \times 10^{-34} \ J \cdot s$ and $m_0 = 9 \times 10^{-31} \ kg$,then the direction of the scattered photons will be: