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LED Circuit

Here i am trying to light a single LED using a 1.5V battery. Forget About LED voltage rating.

What i need here is , where will my ground connection go? what is the significance of that ground and how does that ground works?

I am really newbie to electricals stuff and i find this place to learn.

Kindly help me!

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  • \$\begingroup\$ Does a radio controlled model aircraft have a ground connection? \$\endgroup\$ – Andy aka Jan 14 '16 at 10:21
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    \$\begingroup\$ Reminds me of this :-) \$\endgroup\$ – Curd Jan 14 '16 at 10:48
  • \$\begingroup\$ @Andyaka I am really confused on what actually ground connection is. \$\endgroup\$ – Krishna P S Jan 14 '16 at 10:53
  • \$\begingroup\$ @KrishnaPS: The wikipedia article is a decent start to understand this IMO: en.wikipedia.org/wiki/Ground_%28electricity%29#Electronics \$\endgroup\$ – 0x6d64 Jan 14 '16 at 12:49
  • \$\begingroup\$ In circuit analysis ground is very useful shorthand, but not a truly fundamental thing. Some choices of ground node are more convenient than others. But you can assign any node as ground. Good discussion here. [I'm not talking about earthing and safety.] \$\endgroup\$ – Nick Alexeev Jan 14 '16 at 22:49
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There are basically two meanings for Ground (GND):

  1. an actual electrical connection the the earth ground
    E.g. needed for some types of antennas, power lines etc.
  2. an arbitrary point in the circuit used as reference for voltage measurements or designations
    E.g. in the example of Andy aka there might be a point in the schematic of the radio receiver of a model air plane that is labeled "GND", although there is no way to connect it to the earth. It's just a more of less arbitrary reference point for voltage designations.

It depends on the context what actually is meant.
In very many cases only the 2nd meaning is used.
In cases where the 1st meaning is used it often has also the 2nd meaning too, i.e. the earth ground is used as reference potential for volatge designations.

For your example it makes sense to apply the second case: You can label the negative pole of the battery as GND, but that's arbitrary. You could also do the same with the positive terminal (but not both at the same time).

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Why do you think you need a ground connection? In most cases ground is just a reference, so we could call the negative connection ( the one with the "-") of your battery "ground". There is no need to connect it to anything else. Your circuit will operate on it's own.

For some circuits, ground is an actual connection to the ground, meaning a metal pin you stick in the earth. But this is mainly for the mains circuit (110 or 240 V AC) in your house or for some radio transmitters/receivers. Don't worry about these yet, when such a connection is needed, you will know.

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  • \$\begingroup\$ Then where does the circuit close or end. \$\endgroup\$ – Krishna P S Jan 14 '16 at 10:52
  • \$\begingroup\$ You mean: In circuits where a ground is needed, how is the loop made (or not) ? For radio communications the loop it made complete through the air ! Like this: transmitter > transmit antenna > air > receive antenna > receiver > ground > back to transmitter. For mains circuits the ground loop should be open ! No current must flow. If current flows that is detected and mains is switched off. This is a safety measure for your safety. \$\endgroup\$ – Bimpelrekkie Jan 14 '16 at 12:53

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