<prompt> When the time of exposure is doubled:The number of photons generated is doubledThe energy of photons generated is doubledThe velocity of photons is doubledThe mass of photons is doubled  <response>: EXPOSURE TIME s:Changing the exposure timetypically measured in fractions of a second smodifies the duration of the exposure and thus the number of photons generated. When the exposure time is doubled, the number of photons generated at all energies in the X-ray emission spectrum is doubled. The range of photon energies is unchanged. 