Energy considerations in LC oscillations. How is it in SHM?

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SUMMARY

The discussion focuses on proving that oscillations in an LC (tank) circuit are simple harmonic and demonstrating the conservation of energy in undamped oscillations. The user correctly identifies that the voltage across the capacitor (C) and inductor (L) can be expressed using the equations emf = q/c and emf = -L (dI/dt). By deriving a second-order differential equation, they establish the relationship to simple harmonic motion (SHM). The user also outlines the energy states at different points in the oscillation, indicating that total energy remains constant, with energy stored in the capacitor and inductor represented as E = 1/2 CV² and E = 1/2 LI², respectively.

PREREQUISITES
  • Understanding of LC circuit dynamics
  • Familiarity with simple harmonic motion (SHM)
  • Knowledge of differential equations
  • Basic concepts of energy conservation in physics
NEXT STEPS
  • Study the derivation of the second-order differential equation for LC circuits
  • Explore energy conservation principles in oscillatory systems
  • Learn about damping effects in LC circuits and their impact on energy
  • Investigate the mathematical proof of energy conservation in undamped oscillations
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Students of physics, electrical engineers, and anyone studying oscillatory systems and energy conservation principles in LC circuits.

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Homework Statement


Hi

When you set up an LC (tank) circuit there is oscillation due to charge and discharge of capactor and storage of energy in the inductor.

How do you prove that it is simple harmonic? And also how do you prove (mathematically) energy is conserved in an undamped LC oscillation?


Homework Equations


For C: emf= q/c
For L: emf= -L (dI/dt)


The Attempt at a Solution


emf across C=emf across L
ie, q/c + L (dI/dt) = 0
 
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By setting up an equation of the voltage, using the relevant formulas you've already given, you come to a second order differential equation that, outside of different constants, is equivalent to the second order DE of the harmonic oscillator.
 
Fine thanks. I got the bit on proving it to be in SHM. How should I start to prove that total energy is conserved in a mathematical way?

I can say let at t=0s, energy of system in in C, E= 1/2 CV2 -->1
after 1/4 the time period, energy is fully in inductor, E= 1/2 LI2 --> 2

So Etotal = 1 + 2.

How do I show it is constant for undamped oscillations?
 

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