The momentum of a photon of energy 1 MeV in kg m/s will be

Energy of photon is given byE=hcλ   .    .   .   iWhere  h  is  plank's  constant,  c  the  velocity  of  light  and  λ   its  wavelength.de−Broglie  wavelength  is given  byλ=hp   .     .     .    iiP  being  momentum  of  photon  from Eq.s  i  and  ii,  we  can  haveE=hch/p=pc   or   p=E/cGiven,  E=1  MeV=1×106×1.6×10−19Jc=3×108m/sHence,   after  putting   numerical  values,   we  obtain   p=1×106×1.6×10−193×108kgm/s=5×10−22kgm/s