In this lab we placed marshmallows into the microwave and warmed them up. When we warmed up the marshmallows we observed which parts of the marshmallows rose.
We used this to determine the wavelength of the wave. The length of the part of the marshmallow that rose was 0.12m which corresponds to the wavelength. We use this formula v = f/λ we can solve this equation for the frequency and the resulting equation is v/λ = f. The wave travels at the speed of light which is 3.00 * 10^8 m/s. Once we plug in the velocity of the wave and the wavelength it results in 2.5 GHz. The smallest dimensions of the microwave must be 0.085m by 0.085m. This is assuming that the wave travels along the diagonal of the microwave where the diagonal is 0.12m. The minimum height of the microwave corresponds to the amplitude of the wave.
We also microwaved one cup of water for 30 seconds. To find the total energy in the water we used the equation E_T = MCΔT. Where E is the energy in Joules. M is the mass of the water, C is the specific heat of water, and ΔT is the change in temperature of the water in the reaction. M of the water was 100g. C is 4.186 J/g*°C . The change in temperature was 34°C. This results in the total energy is 14.232 kJ.
We then determined the amount of energy per photon by using the equation E_p=hf, where h is Planck's constant and f is the frequency. This value was 1.659 * 10^-24 J. We can determine the number of photons this way by equating nE_p=E_T. Where n is the number of photons and we can the equation for n which results in
n=E_T/E_p which results in 8.59*10^27 photons.
We can find the pressure by using this equation P=power/Ac, where A is the area and c is the speed of light. Power can be rewritten as dU/dt. Once we plug in these values our pressure comes out to be 3.87 * 10^-7 Pa.
We can determine the pressure exerted per photon by dividing this value by the number of photons.
P/n = 4.51 * 10^-35 Pa/photon.
We then determined the amount of energy per photon by using the equation E_p=hf, where h is Planck's constant and f is the frequency. This value was 1.659 * 10^-24 J. We can determine the number of photons this way by equating nE_p=E_T. Where n is the number of photons and we can the equation for n which results in
n=E_T/E_p which results in 8.59*10^27 photons.
We can find the pressure by using this equation P=power/Ac, where A is the area and c is the speed of light. Power can be rewritten as dU/dt. Once we plug in these values our pressure comes out to be 3.87 * 10^-7 Pa.
We can determine the pressure exerted per photon by dividing this value by the number of photons.
P/n = 4.51 * 10^-35 Pa/photon.
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