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electricity in circuit flows from / to
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electricity in circuit flows from / to

by gosbrut on Mon Mar 17, 2014 6:59 pm

Hello, sorry for this basic question but for me, to be able to continue it is a must.
lets say a mount a circuit using a 9v battery, i connect the positive of the battery to the anode of a led (longer pin) and the cathode of the led to the battery negative.
Are the negative also called ground ?

What are the flow direction of the electricity, from positive of the battery to negative or from negative to positive ?

So, if i need to put a resistor to prevent the light dead, where i need to put between, between negative and led or between positive and led ? why?
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Re: electricity in circuit flows from / to

by hitorque on Mon Mar 17, 2014 7:44 pm

Hello,

Give this a read and see if it answers your questions: http://learn.adafruit.com/all-about-leds/what-is-an-led
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Re: electricity in circuit flows from / to

by gosbrut on Tue Mar 18, 2014 6:05 am

hi i read, ok for a led current goes from pisituve to negative, but, does this way applies to all ?

if i connect a battery possitive to one side of a wire and the another side to the battery negative, this is a circuit, yes ? what will be the flow way, positive to negative or negative to positive ?
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Re: electricity in circuit flows from / to

by adafruit_support_bill on Tue Mar 18, 2014 6:28 am

When current flows in a circuit: Positive charges move from positive to negative. Electrons move from negative to positive.
http://en.wikipedia.org/wiki/Electric_current

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Re: electricity in circuit flows from / to

by franklin97355 on Tue Mar 18, 2014 4:12 pm

This site is a great place to get answers. http://www.allaboutcircuits.com/

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Re: electricity in circuit flows from / to

by gosbrut on Sun Mar 23, 2014 5:56 pm

Great, also need to check

http://en.wikipedia.org/wiki/Electric_current
http://learn.adafruit.com/all-about-led ... s-used-for

Also i read thet "Conventional current flows from positive to negative.
Electronic current which is the flow of electrons flows from negative to positive. This is because on negative terminal, there are more electrons"

But a question again to help me resolve the dude, im a simple circuit consisting in a battery connected to a LED and then back to the battery.
The electricity flow from to ? i mean in what direction or directions ?

From positive to negative by formal, or really from both ends to the opposite ones, i mean both from possitive to negative and from negative to possitive ??

I think goes from negative to possitve, cause in a lot of circuits of battery + LEDs i see the resitors in between the ground and the LED and not in between the + and the LED ,so they resist the flow from Negative to Possitive, is that tru ??
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Re: electricity in circuit flows from / to

by adafruit_support_mike on Sun Mar 23, 2014 11:00 pm

The actual electrons flow from negative to positive.

'Conventional current' is the result of a historical mistake. Back in the 1740s, Ben Franklin did some experiments to decide which direction electricity moves. He got the wrong answer, but was very persuasive, so for about 150 years people got used to calling one side of an electrical field 'positive' and the other 'negative'.

It wasn't until the 1870s that scientists started thinking about a charged particle called an 'electron', and into the 1890s before they had experiments that would measure the charge. Once they did, they found that the electron has the charge everyone had gotten used to calling 'negative'.

Nobody wanted to change all the existing scientific papers, so the names 'positive' and 'negative' have stuck around to this day.. creating much confusion and frustration for millions of people as they first try to understand electronics.
When you void a product warranty, you give up your right to sue the manufacturer if something goes wrong and accept full responsibility for whatever happens next. And then you truly own the product.

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Re: electricity in circuit flows from / to

by gosbrut on Mon Mar 24, 2014 11:40 am

Ye, that story is know but, sorry im ujnclear, it doesnt solve my question

in a simple circuit consisting in a battery connected to a LED and then back to the battery.
The electricity flow from to ? i mean in what direction or directions ?

From positive to negative by formal, or really from both ends to the opposite ones, i mean both from possitive to negative and from negative to possitive ??
gosbrut
 
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Re: electricity in circuit flows from / to

by adafruit_support_bill on Mon Mar 24, 2014 11:57 am

What is the purpose of your question? The conventional model is that current flows from positive to negative. This model is sufficient for understanding the circuit you describe.

At the subatomic level however, the actual 'charge carriers' are the electrons. Since electrons hold a negative charge, they move from negative to positive. This level of detail is important to know if you want to understand the inner workings of semiconductors and other components.

http://en.wikipedia.org/wiki/Electric_current

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Re: electricity in circuit flows from / to

by gosbrut on Mon Mar 24, 2014 6:27 pm

The purpose of my question is to understand Why, in a lot of circuits including the ones from adafruit, -to prevent a LED be die- why the resistor is put in between the negative and the LED instead of between the positive and LED ??
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Re: electricity in circuit flows from / to

by adafruit_support_bill on Mon Mar 24, 2014 6:39 pm

It does not matter which side the resistor goes on. The current flow through the resistor is the same.

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Re: electricity in circuit flows from / to

by gosbrut on Tue Mar 25, 2014 5:02 pm

I completely unknow know, im sorry,

So, you mean that the folowing 2 cases

A)Put the resistor between the negative side of the battery and the LED
and
B)Put the resistor between the positive side of the battery and the LED

Have the same effect ? (prevent the LED to die)

So, it doesnt matter if i put the resistor just after or just before the LED ?
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Re: electricity in circuit flows from / to

by adafruit_support_mike on Tue Mar 25, 2014 5:52 pm

That's correct.

Generally speaking, you can swap the positions of any two parts that are in series with each other without changing the way things look at the outer ends of the connection:

series.jpg
series.jpg (24.57 KiB) Viewed 1506 times

On the left, V1 is the voltage between the top of R1 and the bottom of LED1. I1 is the current that flows through both R1 and LED1.

On the right, V2 is the voltage between the top of LED2 and the bottom of R2. I2 is the current that flows through both LED2 and R2.

If you've just swapped the components around, R1 will be the same as R2 and LED1 will be the same as LED2. If that's the case, then V1 will be the same as V2 and I1 will be the same as I2.
When you void a product warranty, you give up your right to sue the manufacturer if something goes wrong and accept full responsibility for whatever happens next. And then you truly own the product.

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