In this experiment, you will investigate some of the properties of capacitors. To assist you, you have been provided with two (or more) capacitors and an instrument that has within it three parts: 1. voltmeter, 2. coulomb meter, 3. voltage source.

In the normal configuration of the instrument, it measures the voltage across the capacitor that is connected to the input. If left in this configuration for too long, it will cause the capacitor to discharge, so measurements should be made with as little delay as possible.

If the red button is pushed, the instrument becomes a voltage source, and it charges the capacitor. The value is read on the meter, and it can be varied by turning the knob on the instrument. Both the voltmeter and the voltage source have a range of 0 - 10 volts.

When the black button is pushed, the instrument becomes a coulomb meter, and the charge on the capacitor is read. The coulomb meter does this by discharging the capacitor, and recording the charge removed. The range of the coulomb meter is 0 - 1 microcoulombs.

Connect a capacitor to the instrument with the leads provided. Press the red button and set the voltage to some convenient value. Release the button and notice that the voltage decreases very slowly. Then short the capacitor with your fingers. Notice that the briefest touch discharges the capacitor significantly. This demonstrates that you must use care when dealing with the capacitors so you do not inadvertently discharge them.

Recharge the capacitor and press the coulomb meter button. You should obtain a reading which represents the charge that was on the capacitor, in microcoulombs. When you release the button, the reading will fall to zero. Thus if you wish to measure voltage and charge, measure voltage first and then read charge while the button is pressed.

1. Find the capacitance of each of the two capacitors by charging them to a known voltage, and measuring the resultant charge. Record the voltage and the charge for the first capacitor.

a. Then use the relation, C = q/V to find the capacitance. Write down the capacitance of the capacitor. Call the first one measured C1.

b. Now repeat all steps for the second capacitor. Call it C2.

2. Connect the two capacitors in series and measure the capacitance of the combination, as you did for each capacitor in part 1. Compare the result with the calculated value from the relation, , where C1 and C2 are the capacitances of the individual capacitors.

3. When you made the measurements on the series combination in part 2, what was the charge on C1 and what was the charge on C2?

4. When you made the measurements on the series combination in part 2, what was the voltage across C1 and what was the voltage across C2?

5. Connect the two capacitors in parallel and measure the capacitance of the combination, as you did for each capacitor in part 1. Compare the result with the calculated value from the relation, C = C1 + C2, where C1 and C2 are the capacitances of the individual capacitors.

6. When you made the measurements on the parallel combination in part 5, what was the voltage across C1 and what was the voltage across C2?

7. When you made the measurements on the parallel combination in part 5, what was the charge on C1 and what was the charge on C2?