What is the amplitude of an EM wave?

In summary, the conversation is about the derivation of the amplitude of an electromagnetic wave. The speaker is wondering about the amplitude since it is often not mentioned, and how it can be derived. They clarify that they are not referring to intensity, which deals with the number of photons captured by a detector. The link provided gives the relation between the electric field amplitude and intensity. The derivation comes from writing the energy density in terms of E and B, and then using the equation for intensity.
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i always hear about the frequency/wavelength, and the speed of the wave, but i never heard about the actual amplitude of the wave itself? how would one derive this? I'm not referring to intensity... intensity deals with the number of photons being captured by a detector... I'm referring to the actual amplitude of the EM wave itself. if it truly is a wave, it MUST have an amplitude right? what is it? how do i derive it?
 
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Page 11 of this link gives the relation between E-field amplitude [itex]E_0[/itex] and intensity (power per area) [itex]I[/itex] as

[tex]I = \frac{E_0^2}{2 \ c \ \mu_0}[/tex]

Edit added:
The derivation comes from writing the energy density in terms of E and B (as given in any decent E-M textbook), and then using

[tex]\text{Intensity} = \text{Energy density} \cdot c[/tex]
 
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FAQ: What is the amplitude of an EM wave?

1. What is the definition of amplitude in an electromagnetic wave?

The amplitude of an electromagnetic (EM) wave is the maximum distance that the wave fluctuates from its equilibrium position. In simpler terms, it is the strength or intensity of the wave.

2. How is the amplitude of an EM wave measured?

The amplitude of an EM wave can be measured by determining the maximum electric or magnetic field strength of the wave. This can be done using specialized instruments such as a spectrometer or a detector.

3. What is the relationship between amplitude and energy in an EM wave?

The amplitude of an EM wave is directly proportional to the energy carried by the wave. This means that a higher amplitude corresponds to a higher energy level, and vice versa.

4. Can the amplitude of an EM wave change?

Yes, the amplitude of an EM wave can change depending on the source and the medium it travels through. For example, when an EM wave passes through a denser medium, its amplitude may decrease due to energy loss.

5. How does the amplitude of an EM wave affect its frequency and wavelength?

The amplitude of an EM wave does not affect its frequency or wavelength. These properties are determined by the source of the wave and the medium it travels through, while the amplitude only determines the strength or intensity of the wave.

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