Microwave Quiz-Lab

In this lab we are given a problem regarding microwave energy and asked to come up with an answer.

Marshmellows were cooked in a non rotating microwave for 30 seconds. The wave energy produced by the microwave resulted in 3 cooked regions. They were 12 cm apart from each other.

To find the energy of a microwave, a 100g cup of water was heated for 30s and resulted in a change in temperature of 37C.

The microwave is 35x35x23.

Analysis:

the cooked regions of the marshmellows obviously refer to the antinodes of the microwave, where the energy is highest of the resulting standing wave generated from the microwave. The wave has to be a third harmonic because there are no more than 3 cooked regions. Since these are microwaves, the velocity is c, or 3*10^8. the frequency of the waves which must be 24cm in wavelength, should be on the order of 1.25*10^9 Hz, or 1.25 Ghz.

water was heated 37C in 30s
u=mc*dT
the energy created by the microwave was 15kJ

photons travel at the speed of light.
E=hf so the number of photons is the total energy divided by the energy per photon.
we get the result of 6.2*10^26 photons/second

pressure = f/A
since the area = 36cmx36cm the pressure is equal to 2.7*10^-5 N*m