Question

Find the threshold wavelength for a photon to produce an electron positron pair.

Answer 1

Explanation:

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Answer 2

Answer:

The minimum wavelength of a photon to create electron positron pair is equal to 1.02MeV.

Explanation:

When the $\gamma$- rays comes in the electric field of a nucleus, they lead to create electron- positron pair. The minimum energy of $\gamma$- rays is equal to energy of particles individually.

The masses,  $m_{e^{+}} =m_{e^{-}}=m$

The total energy, $E=E_{e^{-}}+E_{e^{+}}$

$E=2mc^{2}$

$E=(2)(9.1*10^{-31})(3*10^{8})^{2}$

$E=1.638*10^{-31}J$

$E=\frac{1.638*10^{-31}}{1.6*19^{-19}}$

$E=1.02MeV$

Therefore $1.02MeV$ is the minimum energy a photon should have to create electron-positron pair.