Marshmallows Lab Quiz

Marshmallows Lab Quiz

Introduction:

The purpose of this experiment is to study the electromagnetic waves by microwave marshmallows and water. We microwaved some marshmallows for approximately 11s. The standing wave on the marshmallows is about 12cm±1cm long from antinode to antinode. Then we microwaved a cup of 100g of water at temperature of 20oC for 10s.  The temperature of the cup of water increases from 20 oC to 57 oC. The measurment of the microwave is 35cm x 35cm x 23cm. Based on these information, we have to determine the frequency, the dimensions of the waves, the total energy content of the cavity, the number of photons per second oscillating in the microwave, and the pressure these photons exert on the side of the microwave.

 

 

Questions:

1.  f = v/λ

       = (3*10^8) /0.12

       = 2.5 *10 ^9 HZ

2. The smallest dimensions of the microwave must be 24 cm x 24 cm x 12 cm. This is assuming that the wave travels along the diagonal of the microwave where the diagonal is 12 cm.

3.  Q = mc (⊿T)

         = (0.1) (4.184)* (57 ^oC - 20 ^oC )

         = 15481 J 

4. E = (hc)/λ

       = (6.626*10^-34)(3*10^8)/ 0.24

       = 8.28 *10^25 J/photons

    Photons/Time = Q/E

                            = 15481 / (8.28*10^-25)

                            = 6.23 * 10^26 photons/s

5. P = Q/T

       = 15481J/ 30s

       = 515.5 W

    

    p = P/Ac

       = 515.5/((0.35*0.35)*(3*10^8))

       = 2.13 *10^-5 N/m