chemistry
posted by Anonymous .
A certain microwave oven delivers 800. watts (J/s) of power to a coffee cup containing 45.0 g of water at 25.0°C. If the wavelength of microwaves in the oven is 9.75 cm, how long does it take, and how many photons must be absorbed, to make the water boil?

heat=45*specificheatwater*(21225) figure that out.
time=heatabove/800
energyineach photon=f*plancksconst
but f=c/lambda
so figure the energy in each photons
number of photons=heat to heat water/energyineach photon 
12