RC circuit and a microfarad capacitor

In summary, the conversation discussed finding the resistance R in a circuit where a 10.0 microfarad capacitor is charged by a 10.0 V battery and reaches a potential difference of 4.00 V in 3.00 s. The formula emf - potential difference capacitor - IR = 0 was used, and the current as a function of time formula was used to solve for R. The calculated result of 587314 ohms was confirmed to be correct, and a few hundred kilo-ohm resistance is common in this type of circuit.
  • #1
lha08
164
0

Homework Statement


A 10.0 microfarad capacitor is charged by a 10.0 V battery through a resistance R. The capacitor reaches a potential difference of 4.00 V in a time interval of 3.00 s after charging begins. Find R.


Homework Equations





The Attempt at a Solution


So basically i got an answer of 587314 ohms..which is kinda a large number...but i don't know the right answer. So what I did was that i used the formula: emf - potential difference capacitor - IR = 0. Then i plugged in the values for the emf and the p.d. capacitor, which gave me 6. Then for the IR part, i plugged in the current as a function of time formula for charging in the 'I' spot and then simply plugged in the R value from the data. Then after calculating, I 'ln' both sides and solved for R...to me, it makes sense, but that's just me..could anyone help me confirm whether the steps I'm doing is correct or even better if they got the same answer as me...??
 
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  • #2
Show your calculations in detail. What formula did you use for the time-dependence of the current? By the way, your result is correct. A resistor of a few hundred kilo-ohm is quite common.

ehild
 
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FAQ: RC circuit and a microfarad capacitor

What is an RC circuit?

An RC circuit is a type of electrical circuit that consists of a resistor (R) and a capacitor (C) connected in series or parallel. The name "RC" comes from the symbols used to represent these components in circuit diagrams.

What is the purpose of a microfarad capacitor in an RC circuit?

A microfarad capacitor, also known as a "uF" capacitor, is used in an RC circuit to store electrical energy. It is able to charge and discharge quickly, making it useful for filtering and smoothing out voltage fluctuations in a circuit.

How does a microfarad capacitor affect the time constant of an RC circuit?

The time constant of an RC circuit is the amount of time it takes for the capacitor to charge to 63.2% of its maximum voltage. A larger microfarad capacitor will have a longer time constant, while a smaller capacitor will have a shorter time constant.

What is the relationship between the capacitance of a microfarad capacitor and its size?

The capacitance of a microfarad capacitor is directly proportional to its size. This means that a larger capacitor will have a higher capacitance, while a smaller capacitor will have a lower capacitance. Capacitance is measured in units of farads, with a microfarad being equal to one millionth of a farad.

Can a microfarad capacitor be used in AC and DC circuits?

Yes, a microfarad capacitor can be used in both AC (alternating current) and DC (direct current) circuits. However, the type of capacitor used may vary depending on the application. For example, AC circuits may require a capacitor with a higher voltage rating to withstand the alternating current, while DC circuits may not have this requirement.

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