First off, it's hard to tell which resistors you are talking about since you haven't provided a schematic to tell us what "r1" and "r2" even are. Instead, you are forcing us to read your mind -- and engineering is NOT about mind reading.
Nor have you given any clue what time of 555 timer circuit you are talking about. Monostable? Astable?
Nor have you told us what it is you want to know about the current through and the voltage across these resistors. Average? Instantaneous? RMS?
So, reading your mind, I'm assuming (another thing that engineering is not about) that you are wanting to measure the average current and voltage for the two timing resistors in a stereotypical 555 astable multivibrator circuit. Is that correct?
All you have to do is look at each phase of such a circuit and derive the equation for the voltage and current in each resistor as a function of time and built up those functions for an entire cycle. Then calculate the averages the same way you would for any function of time.
Dear Mr.WBahnFirst off, it's hard to tell which resistors you are talking about since you haven't provided a schematic to tell us what "r1" and "r2" even are. Instead, you are forcing us to read your mind -- and engineering is NOT about mind reading.
Nor have you given any clue what time of 555 timer circuit you are talking about. Monostable? Astable?
Nor have you told us what it is you want to know about the current through and the voltage across these resistors. Average? Instantaneous? RMS?
So, reading your mind, I'm assuming (another thing that engineering is not about) that you are wanting to measure the average current and voltage for the two timing resistors in a stereotypical 555 astable multivibrator circuit. Is that correct?
All you have to do is look at each phase of such a circuit and derive the equation for the voltage and current in each resistor as a function of time and built up those functions for an entire cycle. Then calculate the averages the same way you would for any function of time.
Dear Bahn,Can you determine the voltage and current in R in the following circuit, assuming that at t=0 the capacitor is completely discharged?
View attachment 99655
You are claiming two contradictory things.Dear Bahn,
Thanks again for your prompt reply.
I am giving below the answer, if i am answer is stupid please correct me.I am just doing my 1st year electronics and am looking forward for your guidance
Now when the capacitor is fully discharged there will no further current flow through the resistor "R" at that INSTANT, so the v{t} will be vcc and i(t) will be v)t) / R
I'm sorry. I didn't realize this was the homework forum. I got here through one of the quick links and it doesn't tell me I'm in Homework.@hp1729: PLEASE! Ask leading questions to guide the TS along the path of figuring out the answers for themselves. Don't just give them answers!
It happens -- it's certainly happened to me more than once.I'm sorry. I didn't realize this was the homework forum. I got here through one of the quick links and it doesn't tell me I'm in Homework.
post: 958713, member: 161605"]You are claiming two contradictory things.You are claiming two contradictory things.
First you are saying that there will be no current flow through the resistor, and then you say that the current will be vcc/R. Since vcc and R are both finite and non-zero, that will be a non-zero current.
When fully discharged, all you know about the capacitor is that it has zero voltage across it -- you have no idea what the current may or may not be in it. That is determined by the rest of the circuit.
So with zero voltage across it, all of the voltage appears across the resistor and, hence, it's current is Vcc/R.
But that is just at that one instant in time. What is it for all other instants in time?
You are claiming two contradictory things.
First you are saying that there will be no current flow through the resistor, and then you say that the current will be vcc/R. Since vcc and R are both finite and non-zero, that will be a non-zero current.
When fully discharged, all you know about the capacitor is that it has zero voltage across it -- you have no idea what the current may or may not be in it. That is determined by the rest of the circuit.
So with zero voltage across it, all of the voltage appears across the resistor and, hence, it's current is Vcc/R.
But that is just at that one instant in time. What is it for all other instants in time?
post: 958713, member: 161605"]You are claiming two contradictory things.
First you are saying that there will be no current flow through the resistor(s), and then you say that the current will be vcc/R. Since vcc and R are both finite and non-zero, that will be a non-zero current.
When fully discharged, all you know about the capacitor is that it has zero voltage across it -- you have no idea what the current may or may not be in it. That is determined by the rest of the circuit.
So with zero voltage across it, all of the voltage appears across the resistor and, hence, it's current is Vcc/R.
But that is just at that one instant in time. What is it for all other instants in time?
So you are being asked to find the average current in a first-order RC circuit but you don't know how to find the instantaneous current as a function of time in a first-order RC circuit? It sounds like whatever course you are in that is assigning you this problem is too advanced for you (meaning that either you have not had the prerequisite course(s) or you didn't learn what you needed to learn from them). You need to take a step back and deal with those deficiencies now, before trying to tackle this problem. You can either try to come up to speed quickly on the transient response first-order circuits and see if you can salvage things or you can drop and take this course (or possibly the prior course) again in order to learn the material.post: 958713, member: 161605"]You are claiming two contradictory things.
First you are saying that there will be no current flow through the resistor, and then you say that the current will be vcc/R. Since vcc and R are both finite and non-zero, that will be a non-zero current.
When fully discharged, all you know about the capacitor is that it has zero voltage across it -- you have no idea what the current may or may not be in it. That is determined by the rest of the circuit.
So with zero voltage across it, all of the voltage appears across the resistor and, hence, it's current is Vcc/R.
But that is just at that one instant in time. What is it for all other instants in time?
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