Capacitor - Resistor circuit.

In summary: I think you are supposed to use it as a shunt for the unknown resistor, and then use the known resistor as a reference.In summary, the student is trying to find the values of capacitance and resistance in a series combination, given the following apparatus. The unknown RC combination (both in the same enclosed box), a known, reference resistor, a variable frequency signal generator (0-1000Hz), and a digital multimeter are used. The student is still stumped about how to approach this problem, and needs help from others.
  • #1

Homework Statement

This is an experiment Ill have to write up later, unfortunately I was out for 2 weeks of lectures due to illness. This is the experiment;

Find the values of capacitance C and resistance R in a series combination, given he following apparatus;

1. the unknown RC combination (both in the same enclosed box),
2. a known, reference resistor, Rref,
3. a variable frequency signal generator (0-1000Hz),
4. a digital multimeter

Homework Equations

I = (Emax . Sin(wt + &)/ |Z|

The Attempt at a Solution

I really am completely stumped guys... I just need to know how to do the procedure and then the calculations should be ok... Any input would be GREATLY appreciated.
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  • #2
We are completely stumped about how we can help you unless you can at least provide a start. It looks like you are supposed to use impedances to find the values, so just use the equations for impedances, and then map out what certain voltages would look like with different frequencies. If you have an op amp then the gain will roll off around the cutoff frequency, and all you have to do if find that cutoff frequency (the -3dB point). If it is just a voltage source you could make say a low pass filter, and find that cutoff frequency.

[tex] Z_c = \frac{1}{j \omega C}[/tex]

[tex]Z_R = R[/tex]
  • #3
Ok, so I guess I am making progress anyway. The resistor will not affect phase at all, so the impedance of that is just R... The capacitor shifts phase by +pi/2... The impedance being 1/wC, and w= 2pi.f... I can use the multimeter to find the ac frequencies and voltages in the circuit (im not allowed to use it for current). I am still a little stumped at how to approach this though, how does the reference resistor come into play?
  • #4
Good so far, what kind of circuit do you want to set up? The reference resistor must come into play because you theoretically don't know its impedance, right?

1. What is a Capacitor-Resistor circuit?

A Capacitor-Resistor circuit is a type of electronic circuit that contains both a capacitor and a resistor. It is used to control the flow of current in a circuit and can be used for a variety of purposes, such as filtering, timing, and voltage regulation.

2. How does a Capacitor-Resistor circuit work?

In a Capacitor-Resistor circuit, the capacitor stores electrical energy and the resistor controls the rate at which the energy is released. When the circuit is closed, the capacitor charges up to its full capacity, and then the energy is released through the resistor. This process repeats as long as the circuit remains closed.

3. What is the time constant of a Capacitor-Resistor circuit?

The time constant of a Capacitor-Resistor circuit is the amount of time it takes for the capacitor to charge up to 63.2% of its full capacity. It is calculated by multiplying the resistance (in ohms) by the capacitance (in farads).

4. What are some common applications of Capacitor-Resistor circuits?

Some common applications of Capacitor-Resistor circuits include filtering out unwanted frequencies in audio and radio signals, creating timing circuits in electronic devices, and stabilizing power supplies to prevent voltage spikes.

5. What are the advantages of using a Capacitor-Resistor circuit?

One advantage of using a Capacitor-Resistor circuit is that it can be used to create a delay in a circuit, which is useful in applications such as flashing LED lights or time delays in electronic devices. It can also be used to smooth out voltage fluctuations and reduce noise in electronic circuits.