There are a number of things that you can do to help improve your ability to have good conversations about circuits. You might think that some of these are nit picky, but I can't begin to emphasize enough the importance and value of having good attention to detail.Hi,
at first switch open , then close . Then after t=0 switch close. I want to calculate time constant when circuit reach steady state. T=RC . R will be 6//1+12 right?
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View attachment 275594
Thank you . I will fix my errorThere are a number of things that you can do to help improve your ability to have good conversations about circuits. You might think that some of these are nit picky, but I can't begin to emphasize enough the importance and value of having good attention to detail.
So, in no particular order, your diagrams show a capacitor but indicate that it is 20 microhenries, which is an inductance. So is this and RC circuit or an LR circuit.
Then, you talk about "the time constant when the circuit reach steady state". The response is an exponential, so in theory it will never reach steady state. In practice, exponential responses are generally considered to have reached their final state after five time constants. This is an arbitrary convention, but after five time constants the system has settled to within nearly half a percent of the final value and that is "good enough" for nearly all purposes. After one time constant it has only gotten a bit under 2/3 of the way to the final value. A better way to phrase this is simply, "the time constant for this circuit."
Your diagrams show that the switch is open at t=0 and closed at t=∞. That really doesn't define when the switch actually closes, since those diagrams would apply equally well to a switch that closed at , say, t=10 s. Your text description does an adequate job of making it clear that the switch closes at t=0. To make it so that the diagrams convey this say notion, show the switch open at T=0- in the first diagram and closed at t=0+ in the second (the - and + are usually written as superscripts).
Finally, get in the habit of tracking your units properly. Resistance is not a pure number -- the units are a part of nearly any physical quantity and should not be left off. So use "R = (6Ω||1Ω)+12Ω". Furthermore, you really should include the parentheses because a slightly different circuit would have "R = 6Ω||(1Ω+12Ω)" and lots of people would sloppily write "R = 6Ω||1Ω+12Ω" in either case without thinking that there is no defined (or widely accepted, even) order of operations between combining things in series and combining them in parallel. Instead, they would see the grouping they intended and assume that their readers would, too, when in reality they are forcing their readers to either become mind readers or guess -- engineering is not about either of those.
NOTE: You might notice that I didn't include units when saying t=0 or t=∞. This is because 0 ms, 0s, 0 hr, 0 years, and 0 centuries are all the same thing. The same when using infinity. The exception is when we are talking about measurements made on a relative scale, such as Celsius or Fahrenheit temperatures.
The symbol you use for ohms is also distracting. It's supposed to be something more like Ω.Thank you . I will fix my error
How many time constants have you been taught is close enough?I want to calculate time constant when circuit reach steady state.
Hi,
at first switch open , then close . Then after t=0 switch close. I want to calculate time constant when circuit reach steady state. T=RC . R will be 6//1+12 right?
Mod:lightened image.
View attachment 275594