CapacitorsConsider two large metal plates which are parallel to each other and separated by a distance small compared with their width.

Area A

The field between plates is 0

E

VL

y

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y00 00

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A

QLL

A

ALbottomVtopV

000

)]()([

0AQL

V

The capacitance is:

L

A

AQLQ

V

QC 0

0

Cylindrical Capacitor

L

A

AQLQ

V

QC 0

0

Capacitors in series: ...1111

321

CCCCtot

Capacitors in parallel: ...321 CCCCtot

22

2

1

2

1Q

CCVW

faradC ][

If you double the amount of charge on a capacitor, how does the capacitance change?

If a 4-F capacitor and an 8-F capacitor are connected in parallel, which has the larger potential difference across it? Which has the larger charge?

A parallel-plate capacitor has a capacitance of 1.0 F. If the plates are 1 mm apart, what is the area of the plates?

1) If a 4-F capacitor and an 8-F capacitor are connected in parallel, which has the larger potential difference across it? Which has the larger charge?

Quiz

2)

Two capacitors are connected in series as shown. If they were initially uncharged, what will be the charge inside the dotted box after connecting points A and B to a battery of voltage V?

A B

3) If the wire connecting the capacitors is bent so that capacitors look like

A

B

how do you now call the arrangement?