PHYSICS 102B LAB – CAPACITANCE
(accompanies Chp. 17, Giancoli’s Physics)
VIRTUAL LABS & SIMULATIONS
1. Go to the Virtual Labs and Simulations webpage:
http://micro.magnet.fsu.edu/electromag/java/index.html
2. Click on the link Factors Affecting Capacitance.
3. Read the one-page lesson.
4. Play with the animation to see how capacitance is affected by dielectric, plate area, and plate distance.
5. Set the variables to the following values:
(a) dielectric to mica, plate area to 0.08 m2, and distance to 0.015 m.
Compute the capacitance, using the formula C = ke0A/d. Your answer should agree with the webpage’s capacitance value.
(b) dielectric to paper, plate area to 0.04 m2, and distance to 0.020 m.
Compute the capacitance. Again, your answer should agree with the webpage’s capacitance value.
6. On the webpage, change the variables; how high can you make the capacitance? List the dielectric, plate area and distance that you used.
7. How low can you make the capacitance? List the dielectric, plate area and distance that you used.
When you are done with the webpage, click on the link on the bottom:
BACK TO ELECTRICITY & MAGNETISM TUTORIALS
This link will take you to the main Electricity and Magnetism page.
Now click on the link Charging and Discharging a Capacitor.
1. Play with the animation.
2. How does the idea of capacitance relate to the flash on a camera?
Engineering Application.
TASK #1
Your task is to design a capacitor that has capacitance of 1.200 nF. Your capacitor has a size restriction: it must be able to fit inside a cube measuring 20.0 cm per side, and the plates must be at least 1.00 mm apart.
Be creative! List the dielectric material, the plate dimensions (length and width), and the plate distance. Show your equation(s) that demonstrate that you have succeeded in designing a 1.200 nF capacitor.
Follow-up question: How much energy could this capacitor store if it were given a potential difference between the plates of 9.0 volts?
TASK #2
Design a capacitor that will store 1.70 mJ of energy when the plates are charged with a potential difference of 240.0 V. (There are no size restrictions.)
List the dielectric material, the plate dimensions (length and width), and the plate distance. Give the resulting capacitance. Show your equations that demonstrate that you have succeeded.