Question

The energy of the em waves is of the order of $15keV$. To which part of the spectrum does it belong?

Answer 1

Step 1: Given:

Energy, $E=15keV=15\times {10}^{3}eV$

$hc=1240evnm$ ($h=6.626\times {10}^{-34}J.s$ is the Planck's constant and $c=3\times {10}^8\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$ is the speed of the light)

Step 2: Formula used:

The equation for photon energy is $E=\frac{hc}{\lambda }\Rightarrow \lambda =\frac{hc}{E}$ ($\lambda$ is the wavelength )

Step 3 :Calculating the wavelength:

$\lambda =\frac{1240}{15\times {10}^3}=0.083nm$

Since, the order of a wavelength is between $10nm$ and $.001nm$, it belongs to X-ray part of the spectrum.