Entropy Change Q: 10 Ohm Resistor @ 300K, 5A for 2 Mins

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SUMMARY

The discussion focuses on calculating the change of entropy for a 10 Ohm resistor at 300K with a current of 5A over 2 minutes. The power dissipated is determined using the formula I²R, leading to a total power of 250W. The change in entropy for the resistor is calculated using the equation dS = dQ rev/T, acknowledging that the process is not reversible. The total entropy of the universe is confirmed to increase, necessitating the consideration of both the resistor and the surroundings for accurate calculations.

PREREQUISITES
  • Understanding of thermodynamics principles, specifically entropy.
  • Familiarity with electrical power calculations, particularly I²R.
  • Knowledge of reversible and irreversible processes in thermodynamics.
  • Basic proficiency in calculus for entropy calculations.
NEXT STEPS
  • Calculate the change in entropy for the resistor using dS = dQ rev/T.
  • Determine the temperature of the surroundings to complete the entropy calculation.
  • Explore the concept of reversible paths in thermodynamic processes.
  • Study the implications of entropy changes in irreversible processes.
USEFUL FOR

This discussion is beneficial for physics students, electrical engineers, and anyone studying thermodynamics and entropy in electrical systems.

bon
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Homework Statement



A 10 Ohm resistor is held at a temp of 300K. A current of 5A is passed through the resistor for 2 mins. Ignoring changes in the source of current, what is the change of entropy in:
(a) the resistor
(b) the universe


Homework Equations





The Attempt at a Solution



Ok so not sure how to do this..

Obviously i know how to work out the total power dissipated (I^2 R)..

dS = dQ rev/T

now not sure what to do... the process isn't reversible right?


im guessing the total entropy of the universe increases..?

help please! :)
 
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bon said:

Homework Statement



A 10 Ohm resistor is held at a temp of 300K. A current of 5A is passed through the resistor for 2 mins. Ignoring changes in the source of current, what is the change of entropy in:
(a) the resistor
(b) the universe
What is the temperature of the surroundings?

The overall process is not reversible. But entropy is calculated for the resistor and surroundings separately. Determine the reversible path between the initial and final state for the resistor and calculate the change in entropy for the resistor. Then find the change in entropy for the reversible path between the initial and final states for the surroundings. You will need the temperature of the surroundings though.

AM
 

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