An ideal blackbody is an object that .a. absorbs most of the energy that strikes it. b. only absorbs energy at ultraviolet ("black light") wavelengths. c. absorbs all the energy that strikes it. d. absorbs a little of the energy that strikes it. e. absorbs exactly half of the energy that strikes it.

Which statement best describes the superposition principle? a.) if two in-phase waves arrive simultaneously at a point, their amplitudes add up b.) if two out-of-phase waves arrive simultaneously at a point, their amplitudes add up c.) if two in-phase waves arrive at a point one after another, their amplitudes add up d.) if two out-of-phase waves arrive at a point one after another, their amplitudes adds up