1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution I am not sure about the relevant equations to be used here. At first sight, I thought I had to apply Stefan's law but then, the question states the power consumed by bulb, not the radiated one. I am completely clueless about what to do here. The first line states the peak wavelength, I have seen peak wavelength being used in Wien's displacement law but I am not sure about this. Any help is appreciated. Thanks!