How Does Maxwell's Current Term Suggest Light is an Electromagnetic Wave?

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SUMMARY

Maxwell's addition of the current term to Ampère's Law demonstrates that light is an electromagnetic (EM) wave by establishing a relationship between changing electric and magnetic fields. The current term indicates that a varying magnetic field generates an electric field, which is foundational to understanding electromagnetic wave propagation. Specifically, the equations \(\nabla \times \vec H = \vec J + \epsilon_0 \frac{\partial \vec E}{\partial t}\) and \(\nabla \times \vec E = -\frac{\partial \vec B}{\partial t}\) illustrate how varying currents produce electromagnetic waves. Light exists at the higher frequency spectrum of these EM waves.

PREREQUISITES
  • Understanding of Maxwell's Equations
  • Familiarity with Ampère's Law
  • Basic knowledge of electromagnetic wave theory
  • Concept of electric and magnetic fields
NEXT STEPS
  • Study Maxwell's Equations in detail
  • Explore the relationship between frequency and electromagnetic waves
  • Investigate the concept of displacement current in electromagnetism
  • Learn about the spectrum of electromagnetic waves and their properties
USEFUL FOR

Students of physics, electrical engineers, and anyone interested in the principles of electromagnetism and the nature of light as an electromagnetic wave.

commelion
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yo

ok progress on the electromagnetic wave front is progressing nicely...finally, but

i have stumbled on a area that i need some help with. see below

when maxwell took amperes law, he added what's known locally ! as the current term, this was done because he realized that a changing magnetic field gives rise to an electric field.

Q how does this current term suggest that light must be an electromagnetic wave ?

if anyone has any consise explanations i would appreciate it, i don't need the maths as i have them in front of me. just think of it as a table quiz kind of answer !

thanks in advance
 
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commelion said:
yo

ok progress on the electromagnetic wave front is progressing nicely...finally, but

i have stumbled on a area that i need some help with. see below

when maxwell took amperes law, he added what's known locally ! as the current term, this was done because he realized that a changing magnetic field gives rise to an electric field.

Q how does this current term suggest that light must be an electromagnetic wave ?

if anyone has any consise explanations i would appreciate it, i don't need the maths as i have them in front of me. just think of it as a table quiz kind of answer !

thanks in advance

Light is just EM wave in much higher frequency spectrum. It is a frequency thing. I am not good enough to explain in plain English, from my understanding:

[tex]\nabla \times \vec H= \vec J +\epsilon_0 \frac{\partial \vec E}{\partial t}\;\Rightarrow \int_c \vec H\cdot d\vec l = I_ C+I_D\;\;\hbox { where it is conduction current and displacement current respectively.}[/tex]

This just said a varying conduction and/or displacement current will produce a varying magnetic field. Which in turn the varying magnetic field will be accompanied with a varying electric field by:

[tex]\nabla \times \vec E =-\frac {\partial \vec B}{\partial t}[/tex]

But nothing is said about the frequency. As said, light is just the upper range of the EM wave frequency.
 

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