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Microwave Oven vs. Cell Phone

  1. Jan 28, 2007 #1
    If the EM waves emitted by a cell phone and a microwave oven have similar frequencies, what does it mean that the waves emitted by the oven contain more energy? I believe that a microwave oven generates about 500 watts, whereas a cell phone generates only about 2 watts. What exactly does that mean? Since the wave frequencies are similar, does this mean that the oven produces waves with greater amplitude? I understand that the waves generated by the oven are amplified inside the oven itself, but I'm trying to understand what makes the waves themselves different to begin with.
     
  2. jcsd
  3. Jan 28, 2007 #2
    The method in which they are generated are different. A microwave oven uses something called a magnetron. It is a type of vacuum tube and uses resonant cavities to set up electromagnetic oscillations. A cell phone uses transistors as oscillators and amplifiers to do the same thing much more precisely controlled and at a much lower power level. As you stated in your first post, the oven generates waves with greater amplitude.
     
  4. Jan 28, 2007 #3
    Huh? What am I missing here? The amount of energy carried by a photon is related to its frequency. The difference between the two items is in the number of photons emitted. Other than that, a photon is a photon and if the frequencies are the same, the energy carried is the same (per photon).
     
  5. Jan 28, 2007 #4

    Gokul43201

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    The OP was looking at it from the classical/wave point of view, where the energy density is proportional to the square of the amplitude of the wave. In the quantum picture, your description is correct - the microwave emits more photons per second per unit solid angle than the cellphone.
     
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