Photon Drive:
A laser generates
1
kW of power continuously
in a beam of light of wavelength
nm.
The beam uniformly illuminates a circular spot
1
cm in radius.
(a)
How many photons does the beam contain per unit volume?
(b)
What is the momentum of a single photon in the beam?
(c)
If the beam is completely absorbed by a blackbody,
what thrust (force) does it exert on the blackbody?