Question

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

• A. Ultraviolet rays
• B. $\gamma$-rays
• C. X-rays
• D. Infra-red rays

Answer 1

Answer: (C)

As $\lambda =\frac{hc}{E}$
where the symbols have their usual meanings.
Here, $E=15keV=15\times 10^{3}V$
and $hc=1240eVnm$
$\therefore \lambda =\frac{1240eVnm}{15\times 10^{3}eV}=0.083nm$
As the wavelength range of $X$-rays is from $1nm$ to $10^{-3}nm$,
so this wavelength belongs to X-rays.