If photons hit one Crookes radiometer (or a solar sail, or similar reflecting and movable object) and are reflected (making it move) would the photons lose any momentum?

If not, where does the kinetic energy won by the radiometer comes from?

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    $\begingroup$ Crooke's radiometer works in a different way. But in the case of the solar sail, the reflected photons get Doppler shifted. $\endgroup$
    – user137289
    Dec 4 '16 at 19:51

The Crookes radiometer does not use radiation pressure (transfer of momentum from photons) as an operating principle. The vanes are suspended in only partial vacuum and the blackened sides are heated by the incident light which causes a force due to the momentum transfer to impinging and then "reflected" gas molecules.

  • $\begingroup$ OK, I got it wrong regarding the Crookes radiometer. But would a series of photons be able to push several solar sails? $\endgroup$ Dec 5 '16 at 0:19
  • $\begingroup$ @Quora Feans - Light pressure is a known effect and can be measured. It has significant effects on spacecraft trajectories and it is envisioned to propel spacecraft with solar sails. See en.wikipedia.org/wiki/Solar_sail $\endgroup$
    – freecharly
    Dec 5 '16 at 3:00

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