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NoTime

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>And do resistors really just turn energy into heat, like my teacher said, or do the just restrict it's flow?

That is how resistors work.

The point of having one in a circuit might be to restrict the flow of energy.

Or the point might be to create a voltage divider where energy flow is not important.

Or some other use.

Also there are ways to restrict energy flow without using resistors.

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chroot

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This site is, in fact, an excellent resource. So are hyperphysics http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html and wikipedia http://en.wikipedia.org.

- Warren

- Warren

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chroot

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Both units can be easily understood by first understanding the meaning of a "coulomb" of charge. A coulomb of charge is the charge on a specific number of electrons -- approximately 6.25 x 10

An ampere is a unit of current; one ampere is defined as one coulomb of charge moving past a given point in one second. It's analogous to the flow of water in a pipe; a larger amount of water moving past a given point in a given time is a larger flow.

A volt is the same unit as a joule per coulomb; if you subject a coulomb of charge to a potential difference of one volt, the electrons (or protons, or whatever) bearing that charge will gain one joule of energy when moving from the high potential to the low. In much the same way, a ton of bricks will gain a specific amount of energy when released from the top of a building and allowed to move from a high gravitational potential to a low one.

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E = IR

E = Electric Potential (Voltage) (Volts)

I = Current (Amps)

R = Resistance (Ohms)

This shows that Voltage is directly proportional to both current and resistance. If you raise I and/or R, E raises as well.

So, for your question above, if you increase the resistance of a circuit and hold the current constant, the voltage will increase.

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Something isn't quite right here....a volt IS the same unit as joule per sec. Also, when 1 coulomb of charge passes through 1 volt of potential difference it does in fact gain energy, since even though the distance of separation between 2 charges decreases, the E-field increases at a greater rate due to the decrease in separation distance (e-field is inversely proportional to distance). Integrate E*dl for a given e-field and you'll see that potential is inversely proportional to distance, which means that as distance decreases as the charges passes through the potential difference, the energy will increase.chroot said:A volt is the same unit as a joule per coulomb; if you subject a coulomb of charge to a potential difference of one volt, the electrons (or protons, or whatever) bearing that charge will gain one joule of energy when moving from the high potential to the low. In much the same way, a ton of bricks will gain a specific amount of energy when released from the top of a building and allowed to move from a high gravitational potential to a low one.

- Warren

However, gravitational potential energy is not a direct analogy to this because gravitational force is constant (constant accelleration for a given mass) unlike electric field, which varies inversely with the square of the distance. So, if you decrease the height by dropping an object, you are going to decrease the GPE. for electrical potential, this is not the case, since e-field strength increases at a higher rate than distance decreases when a charge passes though a potential difference.

So, electrical potential and gravitational potential are sort of reverses of one another, since gravitational force is constant for a given mass as distance varies , whereas electric force varies for a given charge as distance varies. T

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This is one of my favorite references for electrical questions. Bill breaks the definitions down into precise terms and his explanation of how transistors work is a heck of a lot better than what I was originally taught.

I know a few hobbyists who don't have a real understanding of the principles behind the electronics they play with... as for myself, I've been taught electronics three times and I'm ready to go learn it again, for a degree this time.

I know a few hobbyists who don't have a real understanding of the principles behind the electronics they play with... as for myself, I've been taught electronics three times and I'm ready to go learn it again, for a degree this time.

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berkeman

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Catxin -- This is a great book that you should check out. It takes you from the basics all the way up through some moderate level digital and analog electronics. I've read it cover-to-cover, and loved every page:

"The Art of Electronics" by Horowitz and Hill

Amazon: https://www.amazon.com/exec/obidos/...1?v=glance&s=books&n=507846&tag=pfamazon01-20

"The Art of Electronics" by Horowitz and Hill

Amazon: https://www.amazon.com/exec/obidos/...1?v=glance&s=books&n=507846&tag=pfamazon01-20

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Plus, engineering professors get TOO mathematical when explaining things, and textbooks are often the same. This means that the conceptual aspects are overlooked, and students BELIEVE they have the right idea of a concept, but they are in fact thinking of the concepts incorrectly. This is especially the case in electrical engineering, where the concepts are often very abstract.

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Actually, Warren is exactly correct.leright said:Something isn't quite right here....a volt IS the same unit as joule per sec. Also, when 1 coulomb of charge passes through 1 volt of potential difference it does in fact gain energy, since even though the distance of separation between 2 charges decreases, the E-field increases at a greater rate due to the decrease in separation distance (e-field is inversely proportional to distance). Integrate E*dl for a given e-field and you'll see that potential is inversely proportional to distance, which means that as distance decreases as the charges passes through the potential difference, the energy will increase.

Joules/sec = Watts or Power. Volts x Amps = Watts;

Volts = Joules/Coulomb, Amps = Coulombs/second.

Coulombs/second is intuitive as a flow of charge.

Joules/Coulomb is less obvious but it is the amount of

potential energy contained in a coulomb of charge

which is held against a 1 volt potential.

Power is Energy/time, so pushing a coulomb of charge

through a one volt potential in one second is the same

as pushing an object against one Newton of force through

one meter in a second.

They are both one Watt.

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oops. I meant a volt is a joule per coulomb. During that first paragraph I was agreeing with what he said. The second part of the post I was disagreeing when he related electrical potential with gravitational potential. Some of what he said here is incorrect.Antiphon said:Actually, Warren is exactly correct.

Joules/sec = Watts or Power. Volts x Amps = Watts;

Volts = Joules/Coulomb, Amps = Coulombs/second.

Coulombs/second is intuitive as a flow of charge.

Joules/Coulomb is less obvious but it is the amount of

potential energy contained in a coulomb of charge

which is held against a 1 volt potential.

Power is Energy/time, so pushing a coulomb of charge

through a one volt potential in one second is the same

as pushing an object against one Newton of force through

one meter in a second.

They are both one Watt.

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