Comparing Energy Emissions: Microwave Ovens vs. Cell Phones

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Discussion Overview

The discussion centers on the comparison of energy emissions from microwave ovens and cell phones, focusing on the nature of electromagnetic waves they emit, their frequencies, and the implications of their energy levels. Participants explore both classical and quantum perspectives on wave energy and photon emissions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that while the frequencies of the EM waves from both devices are similar, the microwave oven generates significantly more power (about 500 watts) compared to a cell phone (about 2 watts), prompting questions about the implications for wave amplitude and energy.
  • Another participant explains that the microwave oven uses a magnetron to generate waves, which involves resonant cavities, while cell phones use transistors for more precise control at lower power levels, suggesting that the oven's waves have greater amplitude.
  • A participant challenges the idea that the energy carried by the waves can be compared solely based on amplitude, emphasizing that the energy of a photon is determined by its frequency, and the difference lies in the number of photons emitted by each device.
  • Another participant reiterates this point, clarifying that in the quantum view, the microwave emits more photons per second than the cell phone, while the original poster was considering the classical perspective where energy density relates to wave amplitude.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between energy, amplitude, and photon emissions, indicating that the discussion remains unresolved with competing interpretations from classical and quantum perspectives.

Contextual Notes

The discussion highlights the complexity of comparing energy emissions, with participants referencing both classical wave theory and quantum mechanics, which may depend on specific definitions and assumptions about energy and photon behavior.

jslag
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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.
 
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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.
 
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).
 
interested_learner said:
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).
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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