In an accelerator experiment on high – energy collisions of electrons with positrons, a certain event is interpreted as annihilation of an electron – positron pair of total energy $10.2\: BeV$ into two $ \gamma$-rays of equal energy. What is the wavelength associated with each $ \gamma$-ray? $(1\; Bev = 10^9\: eV)$

Question

$\begin {array} {1 1} (a)\;2.436 \times 10^{-18} m & \quad (b)\;2.436 \times 10^{-17} m \\ (c)\;243.6 \times 10^{-17} m & \quad (d)\;2.436 \times 10^{-16} m \end {array}$