How Do You Calculate Current and Energy Decay in a Source-Free RL Circuit?

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SUMMARY

The discussion focuses on calculating current and energy decay in a source-free RL circuit with a resistance of 1 ohm and an inductance of 2H. At t=0, the inductor stores 100mJ of energy, prompting the need to calculate the current at t=1s and the remaining energy at t=2s. The formula I_L(t) = 2e^(-Rt/L) is essential for determining current over time, and understanding the relationship between energy stored in an inductor and current is crucial for solving the problem. The conversion of joules to watts is clarified as joules being equivalent to watt-seconds.

PREREQUISITES
  • Understanding of RL circuit theory
  • Familiarity with the formula for energy stored in an inductor
  • Knowledge of exponential decay in electrical circuits
  • Basic concepts of power and energy in electrical systems
NEXT STEPS
  • Review the formula for energy stored in an inductor: E = 0.5 * L * I^2
  • Learn how to derive initial current from stored energy in inductors
  • Study the implications of resistance on current decay in RL circuits
  • Explore practical applications of RL circuits in electronics
USEFUL FOR

Students in electrical engineering, circuit designers, and anyone interested in understanding the dynamics of RL circuits and energy decay in inductive components.

juicev85
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We just started source free RL circuit analysis in my circuits class (very easy).
However there is a problem in the HW I am not quite sure how to solve.

Problem: The circuit shown consists of a resistance R = 1 ohm and an inductance l = 2H. At t=0, the inductance is storing 100mJ of energy. Calculate (a) i at t=1s (b) the energy remaining in the inductance at t = 2s.

I can easily solve the problems that give an initial current at t = 0s, but i am not sure about the joules. I know joules are watts/second is there some kind of conversion I can perform to get the current so I can use the I L(t) = 2e^-Rt/L formula. This is an easy problem it just comes down to the fact that the prof. didn't mention anything like this in the lecture. So if you guys can give me the tools I am sure I can solve it.
 
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There is a formula for the energy stored in an inductor - it depends on L and I. Check that out in your notes or textbook and use it to find the initial current.
 
It would help if the circuit was shown.


BTW - joules are watt-seconds, or watts (W, power) = Joules (energy)/second
 

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