In this lab, we will measure the time constant of different capacitors in two situations. An oscilloscope is an invaluable tool for testing electronic circuits by measuring. However, since we have swapped the resistor and the capacitor, the grounds are at the same point in the circuit. In this experiment we will study the properties of rc circuits in the time and frequency domain. Connect the oscilloscope probe across the capacitor. Use the exact values you record for your data to make later calculations. A simple rc circuit is drawn in figure 1 with currents and voltages defined as shown. Apply different waveforms produced by the function generator to the oscilloscope and examine them. Theory the oscilloscope, or scope for short, is a device for drawing calibrated graphs of voltage vs time very quickly and conveniently. Rc circuits and the oscilloscope physics lab x objective in this series of experiments, the time constant of an rc circuit will be measured experimentally and compared with the theoretical. Change the settings to obtain the signal as in procedure 56. The capacitor will eventually be charged by the voltage source. Students will learn about the equations that govern capacitor. This lab covers the basic characteristics of rc circuits, including both dc and ac analysis, simulation, and experimentation.
Rc transient circuits rc circuit response to a periodic stepvoltage excitation with its inertialess electron beam, the oscilloscope is particularly adapted for the display of voltage waveforms that are repetitive. Theoretically, the time constant is given by the product of the resistance and capacitance in the circuit, rc. Introduction to the oscilloscope and rc circuits introduction this experiment will lead you through the steps on using an oscilloscope to measure the output of a dc power supply and. In this part, you will observe the exponential decay of the voltage on a capacitor in an rc circuit, using a sophisticated digital oscilloscope. A capacitor is a common electronic circuit component that consists of two parallel plates. This process takes some time which can be determined by considering the capacitance of the capacitor and the resistance of the rest of the circuit. Most students complete part a in week one and part b in week two. Rc in the first part of the lab, you will observe the time dependence of the current in two circuits with large rc. In this position, ch1 is still measuring the voltage. Any two electrical conductors brought near each other form a capacitor.
Show that the capacitive time constant rc has units of seconds. The rc circuit 1 university of north carolina 74 part 2. Capacitors a capacitor is a passive electronic component that stores energy in the form of an electrostatic field. Theory all useful circuits use varying voltages, changing magnitude or even completely reversing polarity.
Be careful when measuring the voltage of the different elements in your. The time constant of an rc circuit is the product of equivalent capacitance and the. The rules for series and parallel combinations of resistors and capacitors will also be explored. The series rc circuit and the oscilloscope we shall use the oscilloscope to study charging and discharging of a capacitor in a simple rc circuit similar to the one shown in fig. Introduction to oscilloscopes lab experiment overview of an oscilloscope introduction an oscilloscope is an electronic test instrument that displays electrical signals graphically, usually. Your calculator and cell phone contain dozens or hundreds of them. Rc circuits and the oscilloscope physics lab x pdf free. Using equation 2, show the mathematical reasoning behind why the time constant.
Rc circuits 3 figure 5 also records the voltage over the resistor. V bc for the battery, but restrict the current range to 10ma 1. Parallel rc and rl circuits 25 lab 6 circuit resonance 33 lab 7 filters. In the second part of the lab, you will use an oscilloscope, a much more sophisticated and powerful laboratory instrument, to observe time behavior of an rc circuit. An oscilloscope is an invaluable tool for testing electronic circuits by measuring voltages over time, and figure 5 shows the schematic for monitoring an rc circuit with an oscilloscope. The natural response of an rc circuit is analogous to that of an rl circuit. The purpose of this lab session is to examine how a capacitor stores its electric. November 12, 2015 phys 20800 section st5 oscilloscope and rc circuits introduction the goal of this lab was to observe the charging and discharging of a capacitor using the. Once you are comfortable with the oscilloscope, set up the circuit below.
Due to limitations in the amplifiers, the oscilloscope s frequency response is limited. Disconnect ch2 from the circuit and connect it to point a as shown in figure 2b. In this lab, we will measure the time constant of di erent capacitors in two situations one where the time constant is. Rc circuits and the oscilloscope physics lab x objective in this series of experiments, the time constant of an rc circuit will be measured experimentally and compared with the theoretical expression for it. The pulsewidth relative to a circuits time constant determines how it is affected by an rc circuit. Dccoupled oscilloscope input circuit and frequency response figure 4. Compare your measured value with the product of rc obtained. A measure of time required for certain changes in voltages and currents in rc and rl circuits. The series rc circuit and the oscilloscope we shall use the oscilloscope to study charging and discharging of a capacitor in a simple rc. Connection of two different coaxial cables to each other. The circuit should reach steady state very quickly, in much less than one second. Students will work in teams of two or three, using a function generator to apply a square voltage wave form 0v to. We will use a twochannel oscilloscope to monitor the important voltages throughout the experiment.
Use the oscilloscope to study a circuit with small rc fast phys 149314942699. Compare your measured value with the product of rc obtained from the individual values of r and c measured earlier and equation. Although we wont touch on it in this lab, rc circuits form the foundation of the. Public circuits, schematics, and circuit simulations on circuitlab tagged oscilloscope. Rc, where r is the circuit resistance your dome light in this case and c is the capacitance, in farads f. So far we observed that in an rc circuit the charge, current, and potential di erence grew and decayed. Oscilloscope connection for alternating current circuit. Parallel rc and rl circuits 25 lab 6 circuit resonance 33. Equipment for lab 7, rc time constant and oscilloscope summary. Record the experimental inductor voltage in table 1. November 12, 2015 phys 20800 section st5 oscilloscope and rc circuits introduction the goal of this lab was to observe the charging and discharging of a capacitor using the oscilloscope as well as being able to measure the impedance of an electric voltmeter by use of a capacitor discharge. Figure 1 shows the firstorder rc circuit whose step response will be studied in this lab. The circuit response is the output voltage divided by the input voltage.
The oscilloscope oscilloscope operation x vs y mode. Chapter 7 rc circuits and the oscilloscope therearetwoimportantconceptsinvolvedinthisexperiment. To experimentally determine the resonance frequency in a series rlc circuit and compare this to the expected resonance value. Swift 16671745 objective to learn to operate a cathode ray oscilloscope. V rc, rl and rlc circuits v university of michigan.
The voltage through an rlc series circuit will be measured as a function of frequency for a fixed applied voltage. Discharge of a capacitor procedure assemble the circuit shown in figure 5. The oscilloscope vision is the art of seeing things invisible. Rc circuits laboratory manual page 2 of 11 3 prelab exercises 3. To experimentally determine the resonance frequency in a series rlc circuit and compare this to. The student will measure the circuit current, the voltages. Drive the function generator with a square wave, and then analyze the wave on the scope as it moves through the rc circuit. Gilbert 15401603 objectives to study some circuit elements and a simple ac circuit. In this series of experiments, the time constant of an rc circuit will be measured exper imentally. In this lab we will only discuss series rlc circuits. Ece 2120 electrical engineering laboratory ii a companion course to ece 2620 electrical circuits ii. Obtain the rc time constant of your circuit using the oscilloscope and the equation for the decay in voltage as a function of time t, where rc is the rc time constant of. Rc transient circuits rc circuit response to a periodic stepvoltage excitation with its. This is a complex number that can also be expressed as a magnitude gain and phase.
In place of the multimeter used in the first part of lab, the oscilloscope will be used. As expected the voltage across the capacitor lags behind the voltage of the. Experiment 10 rlc series circuit resonance in an rlc series circuit objective. The manufacturer simply lists the halfpower point for the oscilloscope without any. On the oscilloscope the vg waveform channel 2 should move to. Such an instrument is obviously useful for the design and. V bc for the battery, but restrict the current range to 10ma oscilloscope lab a.
Oscilloscope and ac circuits introduction now we are going to start using the function generator and the oscilloscope to measure the properties of ac circuits. An oscilloscope and digital multimeter will be used in this lab. Rc, rl and rlc circuits y you have just determined this circuits time constant from the capacitor discharging curve. Also, compute and record the percent deviation between experimental and theory in table 1. Experiment 7 ac circuits look for knowledge not in books but in things themselves.
In this part, you will use a commercial resistor and capacitor not the aluminum. The step response of rc circuits is covered in the textbook. Jul 17, 20 public circuits, schematics, and circuit simulations on circuitlab tagged oscilloscope. Rc transient circuits rc circuit response to a periodic stepvoltage excitation with its inertialess electron beam, the oscilloscope is particularly adapted for the display of voltage. Ee 43100 rc circuits 1 experiment guide for rc circuits i. If the capacitance in the circuit is doubled, how is the halflife affected. Discharge of a capacitor procedure y assemble the circuit shown in figure 5 function. In this experiment, we apply a pulse waveform to the rc circuit to analyse the transient response of the circuit. We will study the transient response to step function inputs for first order rc resistorcapacitor and rl resistorinductor circuits. A capacitor, when connected to a voltage source, will allow charges accumulate on its two sides. Rlc series circuit introduction the objective of this experiment is to study the behavior of an rlc series circuit subject to an ac input voltage. Rl and rc circuits and signals montana state university. Inductors and capacitors are energy storage devices.
Thus, you are measuring the voltage of the resistor in an rc circuit. How to use multisim oscilloscope on a rc series circuit. As expected the voltage across the capacitor lags behind the. Rc, rl and rlc circuits 3 0 2 4 6 8 10 0 2 4 6 8 10 12 14 18 20 t v v 0 12 v 0 t 12 figure 4. Rc circuits and the oscilloscope mercer university physics.
You should receive an oscilloscope, a function generator, a multimeter, one. Sketch the waveforms of vin and vc in your lab figure 1. Replace the potentiometer in the circuit above with a battery obtained from the ta. With the digital oscilloscopes in this lab, the vertical gain knob adjusts the channel. We will study these circuits when the input voltages are suddenly applied or removed transient behavior. Figure 2 shows two sections of the firstorder rc circuit connected in series to illustrate a simple technique to model computer bus systems pci bus, scsi bus, etc. Note that only the resistor part of the rlc circuit is shown. Step response of rc circuits university of washington. The rc circuit department of physics and astronomy. Rc circuits and the oscilloscope mercer university. Series rc circuit construct the circuit shown in figure 2 using the following.
They differ in that a capacitor stores energy as accumulated charge voltage potential and an inductor stores energy in a magnetic field that is due to. In the present exercise we will study the behavior of some basic. This process takes some time which can be determined by considering the capacitance of the. In preparation for the lab do the following activities. Operating instructions for a typical oscilloscope 82. Objective rc circuits and the oscilloscope physics lab x in this series of experiments, the time constant of an rc circuit will be measured experimentally and. Capacitors and the rc circuit capacitors are among the mostcommonly used circuit elements in modern electronic devices. Circuit for rc chargedischarge measurement where vt is the. Lab 5 report oscilloscope and rc circuits phys 20800. Introduction to the oscilloscope and rc circuits introduction this experiment will lead you through the steps on using an oscilloscope to measure the output of a dc power supply and the output of a function generator and then to utilize the oscilloscope to measure the time dependent properties of a simple rc circuit.
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