The expressions for the charge on, and hence voltage across a discharging capacitor, and the current through the resistor, are derived in the 8. Practical 1 rc circuits objectives 1 observe and qualitatively describe the charging and discharging decay of the voltage on a capacitor. Resistor capacitor rc circuits are a feature of all alevel physics exam boards. Notice how it increases slowly over time, rather than suddenly as would be the case with a resistor. Therefore, the hybridization of a capacitor and battery is a reasonable solution to the problem of supplying efficient power sources to evs. Often done in year, the basics of reducing uncertainties can be taken for granted and students can instead focus on using spreadsheets to process data and or use data logging equipment for. When the capacitor is connected to a battery current will flow and the charge on the capacitor. Investigation of the charge and discharge of capacitors. The forms of practical capacitors vary widely but all contain at least two. Capacitance, charging and discharging of a capacitor. The capacitor discharging cycle that a capacitor goes through is the cycle, or period of time, it takes for a capacitor to discharge of its charge and voltage.
Since \q cv\, a large capacitor charged to a huge voltage stores a lot of charge, which will lead to a high initial charging or discharging current, with consequent heating effect. Next, follow the procedure described below on how to use logger pro to collect data for the capacitor charging and discharging. Rc for the time constant of either a charging or discharging rc circuit. The values used in the film and noted above offer a good guide to what works well and safely. Theory and experiment on charging and discharging a capacitor through a reversebiased diode article pdf available in american journal of physics 865 february 2018 with 14,827 reads. The objective of this experiment is to verify the exponential behavior of capacitors during charging and discharging processes. Chapter 11 capacitors charging, discharging, simple. The circuits for charging and discharging the capacitor were set up as specified in the lab manual. It has a slope rate of change which is proportional to the value of the function v no matter where you are on the curve. A charged capacitor can then be discharged by draining the current through its two terminals or connecting some load through its terminals.
We can use kirchhoffs loop rule to understand the charging of the capacitor. Conclusion in this experiment charging and discharging of. Im racking my brain to think of an experiment where im using an rc circuit. With your download, get the 12 best papers relevant to this one, including 8 top related papers. Modeling of a lithiumion capacitor and its charging and. When there is no further flow of charge the capacitor will be fully charged to its final value, figure 10. The below circuit is used to explain the charging and discharging characteristics of a capacitor. The purpose of this experiment is to investigate the charging and the discharging of a capacitor.
In this experiment, charging and discharging of the capacitor with different resistors were observed. Clip the differential voltage probe to the capacitor observing the correct polarity red lead to positive, black lead to negative. To study the charging and discharging of capacitor in rc circuit and to determine the time constant duration. Suppose we have the circuit below, with capacitor c, voltage source v and a toggle switch. Let us assume that the capacitor, which is shown in the circuit, is fully discharged. The exponential the exponential voltage function, which is derived from equation 1, vt v 2 o e tis shown in figure 3. The expressions for the charge on, and hence voltage across, a charging capacitor, and the current through the resistor, are derived in the 8. Rc circuits physics problems, time constant explained, capacitor charging and discharging duration. Charging a capacitor means the accumulation of charge over the plates of the capacitor, where discharging is a completely opposite process. Solve the differential equation, using the capacitor voltages from before the change as the initial conditions.
Suppose you want to charge a 5 volt battery which has a 3200 mah rating. From this expression you can see that charge builds up exponentially during the charging process. If the capacitor is fully charged and then the switch is flicked so that the. Then for a rc discharging circuit that is initially fully charged, the voltage across the capacitor after one time constant, 1t, has dropped by 63% of its initial value which is 1 0. A stopwatch was started when the switch was thrown to start the chargedischarge, and the dmm read at known times until the voltage essentially stopped changing. Often an incorrect value of either resistor or capacitor might be chosen to make readings of the pacitor chargedischarge quite ca difficult to obtain. Theory and practice delmar cengage learning cc tsai 2 introduction when switch is closed at, capacitor charging when switch is closed at, capacitor discharging transient voltages and currents result when circuit is switched. The circuits for charging and discharging the capacitor were set up as specified in the lab. The timer depends on the voltage thresholds on an rc circuit. Charging and discharging of capacitor charging and. Since capacitor currents depend on dv cdt, the result will be a differential equation. So the electrical power consumed by a capacitor can be positive or negative. Electronic and electrical engineering laboratory iii charge and discharge of capacitor student name. You can reset the capacitor back to a voltage of zero by shorting across its terminals with a piece of wire.
Charging and discharging of a capacitor department of physics. Charging and discharging of capacitor electronics tutorials. Capacitor discharge along with radioactive decay, this is a classic practical for taking natural logarithms in order to produce a straight line graph. A capacitor, a resistance box, 2 multimeters, connecting wires, a watch, a dc power source, and a. Im trying to learn about capacitors charging discharging so ive built a very simple circuit where i have an led, a 220 ohm resistor and a 4700uf capacitor in series.
In this experiment a capacitor is charged and discharged and the time taken is. A capacitor is a passive twoterminal electrical component used to store energy electrostatically. The idea is simply to see examine the charging discharging behavior of the capacitor. Build the charging circuit and measure voltage across the capacitor when the switch is closed.
Rc is the time constant of the rc charging circuit. Holkar science college physics department indore 1,579 views 4. This equation can be used to model the charge as a function of time as the capacitor charges. Charging and discharging of capacitor in rc circuits by. Investigatory project report i aim 6 ii introduction 67 iii materials required 7 8 iv theory 8 10 v procedure. After a period equivalent to 4 time constants, 4t the capacitor in this rc charging circuit is virtually fully charged and the voltage across the capacitor is now approx 98% of its maximum value. Every node in a circuit has capacitance to ground, like it or not, and its the charging of these capacitances that limits real circuit performance speed. The objective of this experiment is to verify the exponential behavior of capacitors during charging and. As we saw in the previous tutorial, in a rc discharging circuit the time constant. It consists if two metal plates placed parallel with a dielectric or an insulating medium in between them. Review of charging and discharging in rc circuits an. Pdf the beauty of a diode lies in its voltagedependent nonlinear resistance. The capacitor voltage as a function of time is given by.
Plug the other end of the cable into analog channel 1 in the labpro interface. Consider a circuit consisting of resistor r ohms, capacitor c farads, a voltage source v voltage and a switch as shown below. Pdf theory and experiment on charging and discharging a. Analysis techniques should include loglinear plotting leading to a determination of. This experiment features an rc circuit, which is one of the simplest circuits that. In this experiment a capacitor is charged and discharged and the time taken is recorded respectively. Choose a direction for the current, a direction for circulation around the closed loop, and the signs on the capacitor plates, and draw these on figure 6. The voltage on a charging and discharging capacitor through a.
To study the charging of a capacitor in an rc circuit. Charging a capacitor although no charge actually passes between the capacitor plates, it acts just like a current is flowing through it. Charging a capacitor consider the circuit shown in figure 6. What errors usually occur when doing an experiment. For this, the circuit that we used included the resistor and the capacitor with the power supply. Determine the capacitance of the capacitor, if the voltage across the plates of the capacitor is monitored while it charges or discharges and a curve is fitted to the resulting u vs. Charging and discharging control of liion battery energy management for electric v ehicle application m. Charge and discharge of a capacitor capacitor discharging figure 3. Doc charging and discharging of a capacitor lab report. Deriving the discharging of a capacitor equation take the following circuit that shows a system which can be used to both charge and discharge a capacitor through a resistor. Apparatus dc power supply desktop timer resistor and capacitor digital multimeter circuit breadboard and cable introduction the capacitor. The resulting equation will describe the charging or discharging of the capacitor voltage during the transient and give the.
Questions regarding capacitor and errors electronics. In result, we saw that as capacitor was being charged we saw an increase. When a capacitor is charging, energy is being put into it. To extend the charging process, the resistors were used. Results for charging and discharging, with marked values r 1 m. In both cases the charging and discharging trends do not match. The capacitor discharge equation is an equation which calculates the voltage which a capacitor discharges to after a certain time period has elapsed. Pdf charging and discharging control of liion battery. Capacitors charging, discharging, simple waveshaping circuits source. Draft investigating charging and discharging of capacitors why do this.
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