Question

The wavelength of a photon needed to remove a proton from a nucleus which is bound to the nucleus with 1 MeV energy is nearly:

• A. $1.2nm$
• B. $1.2\times {10}^{-3}nm$
• C. $1.2\times {10}^{-6}nm$
• D. $1.2\times {10}^{1}nm$

Answer 1

Answer: (B)

$1.2\times {10}^{-3}nm$

Here, $E=1MeV={10}^{6}eV,h=6.63\times {10}^{-34}Js,c=3\times {10}^{8}m{s}^{-1}$

$\therefore hc=\frac{6.63\times {10}^{-34}\times 3\times {10}^8}{1.6\times {10}^{19}}=1240eVnm$

As $E=\frac{hc}{\lambda }or\lambda =\frac{hc}{E}=\frac{1240eVnm}{{10}^{6}eV}=1.24\times {10}^{-3}nm$