A spherically shaped light bulb of radius 5 cm emits a symmetric spherical wave with average power 40 watts. (a) (5 points) What is the average power crossing a 1-meter radius closed spherical surface surrounding the light bulb? (b) (5 points) A flat circular power detector directly facing the light source has radius 10 cm and is placed 10 meters away from the source. How much power impinges on the detector?