Energy of gamma rays is given by equation
[tex]E = h\nu[/tex]
here we know that
h = Planck's constant
[tex]\nu = frequency[/tex]
now energy is given as
[tex]E = 4.70 MeV = 4.70 \times 10^6 \times 1.6 \times 10^{-19}[/tex]
[tex]E = 7.52 \times 10^{-13} J[/tex]
now by above equation
[tex]E = h\nu[/tex]
[tex]7.52 \times 10^{-13} = 6.6 \times 10^{-34} \nu[/tex]
[tex]\nu = 1.14 \times 10^{21} Hz[/tex]
now for wavelength we can say
[tex]\lambda = \frac{c}{\nu}[/tex]
[tex]\lambda = \frac{3\times 10^8}{1.14 \times 10^{21}}[/tex]
[tex]\lambda = 2.63 \times 10^{-13} m[/tex]
