Your mistake is that you assumed that the pre-existing coil current is equal to the starting supply current. This is not correct.Hi
Please have a look on the attachment. Where am I going wrong? There is a minor error in my final answer. Could you please help me? Thank you.
Well, even though you solved it "a little carefully" this time, you still solved it the same way as previously. There is a famous quote which says, "insanity is doing the same thing over and over and expecting different results".Hi Steve
I'm still unable to get the correct answer. Yesterday, I was trying to solve the problem hurriedly and didn't have much time to ask follow-on question but I still very much appreciate your response to my request. Now I have solved it little carefully. You see I'm still getting "12", not "24", which I should according to the given answer. Please help me with it. Thank you.
Well, even though you solved it "a little carefully" this time, you still solved it the same way as previously. There is a famous quote which says, "insanity is doing the same thing over and over and expecting different results".
Good work. I follow your point of view now. I misinterpreted one of your steps originally, so I can see how my answer would be hard to follow.
Thanks a lot, Steve.
This was the second RL circuit that I solved. In the past I have solved RC circuits and they were straightforward and didn't led to such 'subtle' problem. So, I think while solving for RL circuits I have to be little careful. The answer I found is incorrect when put t=∞ and I needed to add 3. I understand it now. I'm much grateful.
With best regards
Hi again,I follow your point of view now. I misinterpreted one of your steps originally, so I can see how my answer would be hard to follow.
HiI'm confused by what you wrote out. I see i(t), I(t) and I_T, but it's not clear to me what these are referring to. Is i(t) the coild current or the current in the 4 ohm resistor?
Please label the schematic and identify what i(t) is.
Thank you.So, it looks to me that the coil current is correct, but the method of calculating the current in the four ohm resistor is not. The circuit is not quite the same as a current source driving parallel resisters.
Use v=L di/dt to get the voltage drop on the coil. Then 24 minus v will be the voltage drop on the four ohm resister. Then, divide that by four to get the current in the four ohm resister.
I have looked at it again to check if there was some error in finding the current through the 4 ohm resistor using current divider rule. It looks correct. I understand that it's not a 'regular' current source rather an exponential current source but I still don't find any flaw in the method. I think my method should work. The error comes into play when I use CDR. Why is so? Could you please help me with it?
I meant not factored in to the final step where you use an equivalent circuit.I don't know why you say that the effect of the voltage source isn't factored in.
Thank you very much, Steve.
If you help me with the query in the attachment, then perhaps I would be able to understand where I'm going wrong. Thanks.
We are kind of doing this backwards. You are the one proposing that you have an equivalent circuit that will give you the correct answer. My feeling is that the circuit is not correct. If you propose an equivalent circuit, the burden is on you to prove that it is equivalent and to transform the relevant variables and parameters.Hi Steve
Actually I wasn't able to understand the diagram you gave. But now I have modified the equivalent circuit diagram a little and included the voltage source. Is it any good and can you now tell me which branch has i(t) running through it? Please have a look. Thanks.
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by Kate Smith
by Kate Smith
by Kate Smith