- #1
cgiustini
- 11
- 0
Hi,
I have a qualitative question about RL circuits. I'm trying to summarize how R and L each affect the transient response time L/R from the perspective of energy transfers. I'm pretty confident in my description of the influence of L. I'm not very confident in my description of R in the case of a charging RL circuit, when an EMF is connected to an inductor and resistor in series. I would appreciate if someone could review my thinking.
Description of L's influence:
Inductance L represents magnetic flux through the inductor per unit of current flowing the inductor. Higher L means that more magnetic flux is stored (therefore more magnetic energy) is stored in the inductor per unit of current. Qualitatively, it makes sense for higher inductance to increase the current rise time in a charging RL circuit since the inductor has to drain more energy from the source EMF to achieve a given current. Similarly, when a charged inductor is connected to a resistor, a higher inductance means that more energy is stored per unit of current: therefore, higher inductance means that it will take more time for that energy to dissipate into the resistor.
Description of R's influence:
In a charging RL circuit, the resistance R limits the maximum current that can be set in the inductor. As a result, higher R reduces the total energy that needs to be transferred to the inductor to achieve steady state current. In this case, is this a correct explanation for why the transient response time is inversely proportional to R?
In a discharging RL circuit, increasing R increases the resistor power, ie the rate at which the resistor is dissipating energy from the inductor. Therefore higher R results in a quicker transfer of magnetic energy into thermal energy.
Do these descriptions make sense?
Thanks,
Carlo
I have a qualitative question about RL circuits. I'm trying to summarize how R and L each affect the transient response time L/R from the perspective of energy transfers. I'm pretty confident in my description of the influence of L. I'm not very confident in my description of R in the case of a charging RL circuit, when an EMF is connected to an inductor and resistor in series. I would appreciate if someone could review my thinking.
Description of L's influence:
Inductance L represents magnetic flux through the inductor per unit of current flowing the inductor. Higher L means that more magnetic flux is stored (therefore more magnetic energy) is stored in the inductor per unit of current. Qualitatively, it makes sense for higher inductance to increase the current rise time in a charging RL circuit since the inductor has to drain more energy from the source EMF to achieve a given current. Similarly, when a charged inductor is connected to a resistor, a higher inductance means that more energy is stored per unit of current: therefore, higher inductance means that it will take more time for that energy to dissipate into the resistor.
Description of R's influence:
In a charging RL circuit, the resistance R limits the maximum current that can be set in the inductor. As a result, higher R reduces the total energy that needs to be transferred to the inductor to achieve steady state current. In this case, is this a correct explanation for why the transient response time is inversely proportional to R?
In a discharging RL circuit, increasing R increases the resistor power, ie the rate at which the resistor is dissipating energy from the inductor. Therefore higher R results in a quicker transfer of magnetic energy into thermal energy.
Do these descriptions make sense?
Thanks,
Carlo