Charging Capacitors

Question 1

What equipment should be used?

Answer 1

○ capacitor

○ Resistor

○ Battery

○ Voltmeter

○ Switch

Question 2

What Method should be used?

Answer 2

Set up the apparatus as shown in the diagram.

○ Close the switch and observe and record the voltage reading V at time t=0 and at 5s intervals as the capacitor charges until about 120s have passed.

○ Repeat the experiment twice more and obtain the average V for each t.

Question 3

What graphs and calculations could be done?

Answer 3

○ Plot a graph of V against t. This graph will show an exponential growth curve.

○ V = V0 (1-e^(-t/RC) )

Question 4

What safety precautions could be taken?

Answer 4

Ensure the capacitor is connected with the correct polarity and that its voltage rating exceeds the voltage of the battery used to prevent it from exploding and releasing harmful chemicals.

Question 5

What Improvements could be made?

Answer 5

○ The time constant can be found from the exponential growth curve by finding t when the voltage is approximately 63% of the maximum voltage (the voltage of the battery).