1. The problem statement, all variables and given/known data What will be the irradiance (power per unit area) in the image, if the Sun's irradiance at the sea level is I = 500W/m^2 Lens is 200mm f Sun is 150x10^9 m away Diameter of sun is 1.4x10^9 m 2. Relevant equations 3. The attempt at a solution I know that at the lens the irradiance will be the same i.e. 500W/m^2 but at the image the irradiance will be magnified. I'm not sure how to get there though. I know an image of the sun will be .2m from the lens and the diameter of the image will be .00187m because M=di/do = .2m/150x10^9 = 1.333X10^-12 and 1.333x10^-12 multiplied by the diameter of the sun is .000187m.