1. The problem statement, all variables and given/known data Consider Compton scattering of a photon by a moving electron. Before the collision the photon has wavelength λ and is moving in the +x-direction, and the electron is moving in the −x-direction with total energy E (including its rest energy mc2). The photon and the electron collide head-on. After the collision, both are moving in the −x-direction (that is, the photon has been scattered by 180◦). (a) Derive an expression for the wavelength λ′ of the scattered photon. Show that if E ≫ mc2, where m is the rest mass of the electron, your result reduces to λ′ =hc/E(1 +m^2c^4λ/4hcE) 2. Relevant equations Energy Coservation and Momentum Conservation law. Energy of a particle moving particle and energy of the photon. 3. The attempt at a solution Using the given equations above the same strategy as the one to find the Compton scattering is used. The problem is that the last formula is not the same as the one stated above.