Question

A particular microwave oven delivers 800 watts. (A watt is a unit of power, which is the joules of energy delivered, or used, per second.) If the oven uses microwave radiation of wavelength 12.2 cm, how many photons of this radiation are required to heat 1.25 g of water 1.00°C, assuming that all the photons are absorbed?

Answer 1

I would do this.
Energy of one photon of 12.2 cm
E = hc/wavelength. Remember wavelength must be in meters.
Then Energy needed to heat 1.25 g water =
q = mass H2O x specific heat water x delta T.
So how many photons must be used to acquire q.

Answer 2

Thanks Dr. Bob