Understanding the Need for a Complete Circuit

In summary, electrons are attracted to positive terminals and repelled by negative terminals. If you want a light bulb to light up, you have to connect the negative terminal to the positive terminal.
  • #1
glasslp2000
2
0
Hi,why do we need a complete ciruit required in order to have a continious flow of current.An early reply will be appreciated.

Thanks in advance

Ariel:frown:
 
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  • #2


Originally posted by glasslp2000
why do we need a complete ciruit required in order to have a continious flow of current.
Charge conservation and the principle of relativity:

div j = ∂ρ/∂t

and

∂μjμ = 0
(this is the same as above, but you might not have seen it, and it emphasises the relativistic requirement)

Otherwise, electrons would disappear at one point in space and then reappear at another point in space, and this would violate conservation of charge under the principle of relativity (see simultaneity).
 
  • #3
I really couldn't disagree less with Turin.

(That means I agree with Turin.)

But here's an answer with no tensor calculus involved:

Connect a light bulb to the negative terminal of a battery. The light bulb is neutral, and the electrons in the battery are repelled by each other. (Opposites attract, likes repel.) So some of them will run through the wire to the light bulb. But pretty soon, there's about the same amount of charge everywhere, or rather, the electrons have arranged themselves so that they are least repelled by each other. Imagine attendees of a party that ended badly, awkwardly trying to avoid each other at another party the following week.

It's a stable configuration, once they've all found a corner to sulk in, but not very conducive to light bulbs getting lit up.

To make the light bulb glow, you connect the other side of it to the positive terminal. The electrons are all attracted to this beckoning beacon, and they are much more concerned with reaching the positive terminal than they are with avoiding each other, and to get there they are even willing to pass through the thin filament of the light bulb, heating it to white hot in the process.

But unless there's a positive terminal to go to, they ain't movin'.

Forgive me if it seems that I'm anthropomorphizing electrons; I'm actually electrosizing humans.

P
 
  • #4
Originally posted by rocketcity
Forgive me if it seems that I'm anthropomorphizing electrons; I'm actually electrosizing humans.

P

That should go in the who wants to be a liar thread.
 
  • #5
thankyou

Thankyopu everyone:smile:
 

1. What is a complete circuit?

A complete circuit is a path that allows electricity to flow from a power source, through a load (such as a light bulb or motor), and back to the power source.

2. Why is a complete circuit necessary?

A complete circuit is necessary for electricity to flow and for a device to function properly. Without a complete circuit, electricity cannot reach the load and the device will not work.

3. What happens if there is a break in the circuit?

If there is a break in the circuit, such as a disconnected wire or a broken component, electricity cannot flow and the device will not work.

4. How can I test for a complete circuit?

You can test for a complete circuit by using a multimeter or a continuity tester. These tools can detect if there is continuity (a complete path for electricity to flow) in a circuit.

5. Can a circuit be complete without a power source?

No, a circuit cannot be complete without a power source. It is the power source that provides the energy for electricity to flow through the circuit and power the device.

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