Question

A totally reflecting disk has radius 6.00 μm, thickness 2.00 μm, and average density 5.00×102 kg/m3. A laser has an average power output Pav spread uniformly over a cylindrical beam of radius 2.00 mm. When the laser beam shines upward on the disk in a direction perpendicular to its flat surface, the radiation pressure produces a force equal to the weight of the disk.

What value of Pav is required?

What average laser power is required if the radius of the disk is doubled?

Answer 1