## Calculate the time constant of each circuit and use the graph to determine two points separated by RC value and look at the difference in voltages that correspond to RC on the graph.

RC Circuits

Press the down arrow on the picture

Then open the file

Connect the circuit shown on the white board or the attached picture

Notice that there are two switches S1 is in series with the 18 volt battery

S2 is in series with  a 100 ohm resistor ( which you can set).

Make the capacitance 0.2 or maximum

Leave S2 open connect a voltmeter across the capacitor and notice that it will record 18 volts as the capacitor will charge quickly.

Bring a timer the (yellow stopwatch shown), or use the stopwatch on your phone

Open S1 and notice that the voltage remains at 18 volts as long as S2 is open because the capacitor keeps the charge on the capacitor,

Close the switch S2 and start the timer as soon as possible and record the value of the voltage at that time and then every 5 second.

Make a table of the voltage across the capacitor as a function of time

Get around 12 readings or more.

Plot a graph of Vc on the y axis with time on the x-axis. You can ignore the first or the second reading and start the graph making the third reading represents the voltage at t=0 (if it is difficult for you to get the value of Vc and time together for the first or second points) practice or cooperate with your partner first.

Repeat the above using a resistor of 60 ohms.

Plot the two graphs on the same graph paper or screen if you can

Choose two voltages on the first graph and calculate the time between them from the graph.

Use the discharge equation to find the value of the capacitor and compare it with the value you have.

Repeat  the above procedure using R = 60 ohms and draw a second graph.

Find the average value of the capacitor and compare with value you have. Find percentage error.

Calculate the time constant of each circuit and use the graph to determine two points separated by RC value and look at the difference in voltages that correspond to RC on the graph and find the ratio of

Final voltage/initial voltage

Do this for the second graph.

Look at the example on the white board.

Submit individually or in groups of two