Hello! I've been working on this physics problem for a physics II course and I'm stumped. Maybe someone can assist? 1. The problem statement, all variables and given/known data A small insulated copper sphere of radius 0.001m is illuminated with radiation with wavelength 300nm. What is the maximum charge accumulation on this sphere? 2. Relevant equations The only equation I can do unit analysis on and get a coherent answer is E = hc/λ I'm not sure which equation to use next, however I think that: E = kq/r^2 is an important equation for this problem. Finally, the surface area of a sphere: A = 4[itex]\pi[/itex]r^2 3. The attempt at a solution Initially, I calculated the energy associated with the radiation: E = hc/λ = hc/(3e-7) = 6.62e-19 J Then, I divided the sphere's surface area (A = 4[itex]\pi[/itex]r^2 = 1.26e-5 m^2) to get a flux (also apparently called irradiance) of light over the sphere's surface. Flux = 5.27e-14 J/m^2 Now, I'm not sure how to proceed. I'm having difficulty conceptualizing how irradiance influences charge on an insulated object. I thought that in order for charge to accumulate on an insulated object, an electric field must be present. My understanding is that light is electrically neutral and by itself does not create electric fields. Could the copper substrate be significant in creating a charge through being ionized? I feel like that point is beyond the scope of the question but I'm completely lost on how to proceed. Thanks for any help anyone can offer!