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Name: Jorge
Status: student
Grade: 9-12
Location: FL
Country: N/A
Date: 8/10/2005
Question:
How can the total amount of mobile charge in a capacitor be the same after charging as before charging?

Replies:
Jorge,

All capacitors have two kinds of charges: protons (positive charges), electrons (negative charges). An UNCHARGED capacitor has equal numbers of protons and electrons on each side. Each side has a charge of zero. Each side is balanced.

When you charge a capacitor, you move some electrons from one side to the other (through the circuit, often a battery). The protons stay put. Now one side has a POSITIVE charge and one side has a NEGATIVE charge. The TOTAL charge for the whole apparatus is still zero. The total number electrons and protons are the same. When you charge a capacitor, you do not add or remove charge: you rearrange the charges.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College


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