The energy of an $X$-ray photon of wavelength $1.65 \mathring{A}$ is ....... $keV$. $(h = 6.6 \times 10^{-34} \ J \cdot s, \ c = 3 \times 10^8 \ m/s, \ 1 \ eV = 1.6 \times 10^{-19} \ J)$ (in $.5$)

The binding energy of the innermost electron in tungsten is $40 \text{ keV}$. To produce characteristic $X$-rays using a tungsten target in an $X$-ray tube,the potential difference $V$ between the cathode and the anti-cathode should be:

Assertion: $X-$rays travel with the speed of light.
Reason: $X-$rays are electromagnetic rays.

Why is a direct $X$-ray photograph of the intestines not taken by a radiologist?

$X$-rays of wavelength $\lambda$ are reflected from parallel planes of atoms in a crystal with spacing $d$ between two planes, as shown in the figure. If the two reflected beams interfere constructively, then the condition for maxima will be (where $n$ is the order of the interference fringe):

If ${\lambda _1}$ and ${\lambda _2}$ are the wavelengths of characteristic $X$-rays and gamma rays respectively,then the relation between them is