Peoples Physics Concepts

http://www.ck12.org Chapter 15. Electric Circuits: Capacitors

C=

κεoA

d

C=

1 ∗ 8. 85 ∗ 10 −^12 F/m∗(.25 m)^2

.01 m

C= 5. 5 ∗ 10 −^11 F

Now we can find out how much charge can be stored on the capacitor.

Q=CV

Q= 5. 5 ∗ 10 −^11 F∗12 V

Q= 6. 63 ∗ 10 −^10 C

(b): The new capacitance will just be 80x the original capacitance because that is the dielectric constant of water.

We can use this to calculate how much charge can be stored on the submerged capacitor.

Q= 80 CV

Q= 80 ∗ 5. 5 ∗ 10 −^11 F∗12 V

Q= 5. 31 ∗ 10 −^8 F

As you can see, the capacitance of these plates is pretty small. Most capacitors have very thin, but very long metal

sheets that are rolled up into a cylinder and separated by only a few millimeters; this provides a much greater

capacitance in a much smaller volume.

Watch this Explanation

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/1819