How Do You Calculate the Total Charge in a Solenoid with Time-varying EMF?

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SUMMARY

The discussion focuses on calculating the total charge passing through a solenoid with a time-varying electromotive force (emf) described by the equation E = E.e^-kt. Participants explore the relationship between emf, inductance (L), and current (I) using the equations E = LdI/dt and I = dQ/dt. The solution involves manipulating these equations to express the current as a function of time and subsequently integrating to find the total charge. The key takeaway is the necessity of understanding the time-dependent nature of the emf in the solenoid.

PREREQUISITES
  • Understanding of inductance (L) in electrical circuits
  • Familiarity with the concept of electromotive force (emf)
  • Knowledge of differential equations and their application in circuit analysis
  • Proficiency in integrating functions to find total charge
NEXT STEPS
  • Study the derivation of the current function I(t) = E/R(1 - e^-Rt/L)
  • Learn about the relationship between current, charge, and time in electrical circuits
  • Explore the concept of self-inductance and its effects on circuit behavior
  • Investigate the application of Laplace transforms in solving time-varying circuit problems
USEFUL FOR

Students in electrical engineering, physics enthusiasts, and anyone studying electromagnetic theory who seeks to understand the dynamics of solenoids and time-varying circuits.

latitude
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Homework Statement



A selfinduced emf in a solenoid of inductance L changes in time as E = E.e^-kt. Find the total charge that passes through the solenoid, assuming the charge is finite.



Homework Equations


E = LdI/dt
U = 1/2LI^2
I = dQ/dt


The Attempt at a Solution


I'm pretty stumped by this one, honestly. I thought I might have to use I(t) = E/R(1 - e^-Rt/L) somehow. I don't really understand how the emf is changing in time?
 
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latitude said:

Homework Statement



A selfinduced emf in a solenoid of inductance L changes in time as E = E.e^-kt. Find the total charge that passes through the solenoid, assuming the charge is finite.



The Attempt at a Solution


I'm pretty stumped by this one, honestly. I thought I might have to use I(t) = E/R(1 - e^-Rt/L) somehow. I don't really understand how the emf is changing in time?

Well I am not sure if the Es in E=E.e-kt are the same but you can do this

L(dI/dt)=Ee-kt and then do something similar with dQ/dt
 

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