Jump to content
Electronics-Lab.com Community

A "silly" question about a resistor and a led position


Recommended Posts

from one software person to another.
Series = Single step modal program
Parallel = Multi-step / Time slice / Non-Modal Program


To really start you off on the right foot.
Resistors are additive.  If you need 10,000 ohms (10K)
and you only have a box of 1000 ohm (1K) resistors.
You could string 10 of them together and get a total of 10K ohms.
IT wouldn't matter where the diode went. 

Ohm said:  Current = Voltage divided by Resistance (I = E/R)
He never said anything about order.
Now Norton Thevenin, those two had a lot to say about resistors and order.
Look them up.

Good luck, and ask more questions.


Link to comment
Share on other sites

;D  am I?  ???

No. Just that the T&N theroms (When it comes to Resistor networks) are all about placement.  In a straight line Series circuit there is no difference.

But in a mesh where the currents will be divided amoung different branches, the LED might not even light because the potentials could result in unexpected polarity issues.

Just forewarning that there are times when it is critical, but not here.



Link to comment
Share on other sites

Hey Atrats.

I'm no noob at electronics, and I am still confused by what people are saying here. Way too complicated.

Here's my two cents: Don't think about electrons (or any charges for that matter). There are two reasons for this.

The first is that in circuit diagrams and tutorials current is always shown to flow from the higher voltage towards the lower voltage. That is, in the direction opposite to electron flow! They call this diagramatic current flow from higher to lower voltage "conventional current", and if you are worrying about electrons moving around you will only end up confusing yourself. There are very few applications where you need to consider the actual charges (like electrons) that move to make an electric current.

Secondly, in a simple loop circuit like the battery/LED/resistor, you can consider that all points in the circuit have exactly the same current flowing through them. Think of water flowing freely around a loop of pipe - if you squeeze the pipe in one place, the water slows down everywhere in the pipe. The same goes for electric current. You can put the resistor anywhere in the loop, and the current is reduced everywhere. As you think of water, and not of molecules, think of electric current, and not of electrons.

In fact, look to water as a way of visualising electricity - the rules of electric current and water flow are so similar that you probably know a lot more about electricity already than you think.

What makes a water flow? Pressure difference. What makes electric current flow? Voltage difference (mostly referred to as "potential difference). There's your first analogy, water pressure is the analogue of electrical potential, otherwise known as "voltage". To create a pressure diferrence in water, you either use a pump or gravity. In an  electrical circuit, you could use a battery.

Current, on the other hand is how much stuff passes a point in a circuit each second. For stuff like water, you might measure that in "litres per second". For electrons (each of which carries a charge measured in "Coulombs"), you would say "Coulombs per second". Of course, nobody says "Coulombs per second" - rather we say "Amperes" or just amps.

Kirchoff pointed out that, just like water, whatever stuff flows into some point in a circuit must also come out of it. That's common sense, of course. You knew that already, and now you know that the same applies to electric current. You see it in action right here in your battery/LED/resistor circuit. It's not possible to have a different current flow at one point than at another!

There are many many little "laws" like this that you probably see in daily use around you, which seem like common sense, and which apply equally to electronics. I'll continue if you want some more pointers.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...