# Understanding Positive and Negative charges

Discussion in 'Electronics Homework Help' started by alistaircook, Dec 26, 2016.

1. ### alistaircook

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Dec 26, 2016
I've recently been trying to get into electronics, but there is something I just cant get my head around, which are positive and negative charges.The questions I have are : whats the difference between them, why do we use both and not just one(i thought only electrons are useful) and are the positive charges all protons or what?
I know these questions are pretty stupid and I have probably wrote them in the wrong section , but I am really confused and any help in this area would be greatly appreciated.

2. ### davennModerator

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1,956
Sep 5, 2009
hi there
welcome to EP

Atoms are initially neutral, that is, they have an equal number of protons and electrons, they become positively charged when they lose electrons. An Ion is a charged particle. A cation is the name for a positively charged ion, and a negatively charged ion is a anion ... an electron

https://en.wikipedia.org/wiki/Ion

it is the electrons ( the negative charges) that are mobile and move through a circuit.

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3. ### Laplace

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Apr 4, 2010
In my opinion, the concept of positive & negative charge is more useful in chemistry or physics than in electronics. It is also somewhat unfortunate that physical current flow is the movement of negative charge electrons because the standard convention for circuit analysis is to assume positive current flow, i.e. the opposite of what electrons do. (And if you get into semiconductor physics, there is hole current which could be described as the flow of the absence of electrons.)

For those just starting in electronics, it's not too early to regard current merely as an abstract mathematical quantity, and as something that can be measured with a VOM. Learn Kirchhoff's Laws, nodal analysis, and the differential equations of capacitor & inductor circuits. That will be a good foundation for electronics, and none of it depends on positive/negative charge concepts. Remember: In electronics, current flow is positive (unless you're in the U.S Navy).

alistaircook likes this.

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Dec 26, 2016
Thank you

5. ### Ratch

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Mar 10, 2013
An atom is the smallest unit of matter. Its constituents are electrons, protons, and neutrons. These three atomic particles are thought to consist of still other subatomic particles. The movement of electrons, protons, and neutrons cannot be thought of as abstract concepts, because they have both mass and, with the exception of neutrons, also charge. Electrons and protons are charge carriers, and have equal and opposite charges, which are named positive and negative. There are just as many positive charges in the universe as negative charges. Charge movement is called current. The mathematical convention is to assume that charge is positive and moves from a positive to negative voltage. If you have to know the real direction of the charge, then keep the same calculated direction if the charge carrier is positive, and reverse the direction if the charge carrier is negative.

Moving charges cause magnetic fields to form, and an accumulation of charges cause an electrostatic field to exist. A moving stream of neutrons will not cause a magnetic field, and an accumulation of neutrons will not form an electrostatic field. Electric charges also enable the transfer of energy along conductors. A stream of neutrons will not transfer any electrical energy and cannot be moved by voltage.

Ratch

Last edited: Dec 28, 2016
alistaircook likes this.

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Dec 26, 2016
Thanks