Understanding Displacement Current in Charging a Capacitor

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SUMMARY

The discussion focuses on calculating the displacement current in a capacitor being charged by a 0.1 A current, with square plates measuring 5 cm on each side and a separation of 4 mm. The key equations involved include the electric flux, represented as Φ_E = ∫∫ E · da, and the relationship between displacement current (Id) and the time rate of change of electric flux. The confusion arises regarding the relevance of the plate dimensions and the application of Maxwell's equations, particularly the integral forms involving CurlB.

PREREQUISITES
  • Understanding of electric flux and its mathematical representation
  • Familiarity with Maxwell's equations, particularly the displacement current concept
  • Basic knowledge of calculus, specifically double integrals
  • Concept of current (I) and its relationship to displacement current (Id)
NEXT STEPS
  • Study the derivation and application of Maxwell's equations in electromagnetic theory
  • Learn about the concept of displacement current in detail, including its significance in capacitor charging
  • Explore the mathematical techniques for calculating electric flux and its time derivative
  • Investigate the physical implications of electric fields in capacitors and their role in circuit design
USEFUL FOR

Students of electromagnetism, electrical engineers, and anyone interested in the theoretical foundations of capacitors and displacement current in electrical circuits.

frozenguy
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Homework Statement


A 0.1[A] current is charging a capacitor that has square plates 5cm on each side. The plate separation is 4mm. Find (a) the time rate of change of the electric flux between the plates and (b) the displacement current between the plates.

The Attempt at a Solution


So I had hints from the teacher, and got the answer but I'm a little confused as to what I did.. Could someone help me out?
Why does the 4mm not come into play? or the 5cm?
Is I=Id always? Usually?
What was the point taking double integral of CurlB? And what equals muI+muId?


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All you really have to do is worry about the displacement current. The other stuff is extra information for what you actually have to solve. The double integrals come from the integral forms of the Maxwell equation, it's really just a starting point.

I don't see how you got the right answer when your work is so funky.

[tex]\Phi_E = \int\int E \cdot da[/tex]

gives the electric flux. Take the time derivative of that and multiply by epsilon for the displacement current.
 

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