1. The problem statement, all variables and given/known data The light from a bulb shines equally in all directions. If 20W of light is given off, what will the intensity be 12m from the lamp to 2 significant figures? (Consider the shape of the region illuminated if the light hits this surface after travelling 12m in all directions.) 2. Relevant equations 3. The attempt at a solution 20 / pi * 122 = 0.044 W/m2. Incorrect. I suppose this value would give me the average intensity over the entire area. Halving it should then give me the furthest intensity. 0.022 W/m2, still incorrect.