RC circuit

RESISTOR-CAPACITOR CIRCUIT

  I.    Introduction:

         By this time, you are expected to be familiar already with the different kinds of connections. To have a review, there are three types which are series (e.g. Christmas lights), parallel (lights in our homes) and network or the combination of series and parallel. Of course, connections can be more complicated than network in which one of its examples is RC circuit.

         As a review, capacitor is a circuit element that functions like a battery that can store electrical energy. Resistor, on the other way around, is also a circuit element that functions as regulator to current because of its known resistance. Combining the two and there goes the type of circuit named as RC circuit.

II.  Definition:

         Resistor-Capacitor circuit or also known as RC circuit is a type of connection wherein there are capacitors and resistors as obviously it suggests to its name. This type of circuit is used for filters and timing since this involves time delay.

III.    Schematic Diagram:

https://goo.gl/QpquBz

IV.          Formulas:

          The time delay depends on the circuit elements. Therefore, this has built the relationship between resistance and capacitance which is Resistance x Capacitance = Tau or τ. (RC=τ) Time constant is defined as the time required to charge and discharge a capacitor.

          We have known already the process of charging and discharging a capacitor since we have solely discussed it at the previous chapter about capacitor. To give a review, when a switch is closed, current is zero and the capacitor is charging. As the switch is opened, current will be read since the capacitor is discharging. Below are the formulas involved in charging and discharging a capacitor.

https://goo.gl/n6a1Pb

http://goo.gl/C2Et

 

V.  Application:

 

Common applications of RC circuit are the following:

1. Series lights. The blinking of series lights during Christmas involves timing.

http://goo.gl/Bgf6BK

2. Pacemakers. Used to control the heartbeat for normal beating.

http://goo.gl/IN4HF4

3. Windshield wipers. Used to clear the glass when travelling in rain.

https://goo.gl/3b3ggj

VI.     Laboratory Experiment

I.          Introduction:

         RC circuit is a circuit comprises of resistor and capacitor. The capacitor charges through the resistor and gets full depending on its capacitance in a certain time called time constant. It will also eventually discharges that can generate electricity for a period of time.

II.      Objectives:

         a.      Set up an RC circuit

         b.      Perform the charging and discharging of a capacitor

         c.      Tabulate the data using table for the charging and discharging

        d.      Graph the data being tabulated. 

III.    Materials: 

                    a.      Power supply 

                    b.      Capacitor 

                    c.      Resistor 

                    d.      Alligator clips 

                    e.      Multitester 

                    f.       Stopwatch

II.               Procedures:

        1.      Determine the resistance of the resistor.

        2.      Set-up the resistor and capacitor in series.

        3.      Charge the capacitor for one minute and take the voltage for every 5 seconds interval.

        4.      Discharge the capacitor for one minute and take again the voltage for every 5 seconds interval.

        5.      Record the data using table for charging and discharging.

III.              Data and Results:

 

TABLE 1: V_OUT: 4.5 V, R₁ = 5500 Ω, R₂ = 180 Ω, C= 4700uF

 

t (s)	VDROP , Charging	VDROP, Discharging	Current, Charging
5	0.4 V	2.0 V	6.6 x 10-4 A
10	0.6 V	1.8 V	5.4 x 10-4 A
15	1.0 V	1.6 V	4.50 x 10-4 A
20	1.2 V	1.4 V	3.74 x 10-4 A
25	1.4 V	1.2 V	3.10 x 10-4 A
30	1.6 V	1.1 V	2.60 x 10-4 A
35	1.8 V	1.0 V	2.13 x 10-4 A
40	2.0 V	1.0 V	1.77 x 10-4 A
45	2.05 V	0.9 V	1.46 x 10-4 A
50	2.2 V	0.8 V	1.21 x 10-4 A
55	2.2 V	0.8 V	1.01 x 10-4 A
60	2.2 V	0.6 V	8.35  x 10-5 A

VI. Graphs:

Observation:

             I observed that during charging, the voltage reading is really increasing and the same for discharging in which it was also decreasing. The charging was approximately 0.2-0.3 and during discharging it was also discharging for about the same range.

Generalization:

             The time used in charging will be the time required to discharge it.

          

References:

                             

Retrieved on September 6, 2015 from http://www.wisegeek.com/what-is-a-rc-circuit.htm

Retrieved on September 6, 2015 from http://www.electronics-tutorials.ws/rc/rc_1.html

Retrieved on September 6, 2015 from https://www.youtube.com/watch?v=OIpHPsnLlNU