# Encountered Confusion upon Learning the Electron Flow of the "Lamp Dimmer Circuit" in the E-Book

Discussion in 'General Electronics Chat' started by Mohammad Nur Bramasta, Nov 29, 2015.

Nov 29, 2015
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So I'm really new at electronics, and I'm trying to learn from the very basic...
As I went to Vol.3, Chapter 3 (http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/rectifier-circuits/), and looked at this picture:

I "read" this as the electron "started" flowing from the source to the lamp first then to the diode. As opposed to the diode first (related to my understanding of the electron flow convention, no way for the electron to flow to the diode first as the diode will block). Wouldn't anything different (i.e. light being dimmed) happened then? Since the electricity had already go to the lamp first?

2. ### dl324 Distinguished Member

Mar 30, 2015
3,376
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The tutorials use electron current, not conventional current.

With the switch in the dim position, the diode only conducts on the positive half of the sine wave.

The order of the diode, switch, and lamp aren't critical as no current flows unless the "loop" is closed.

Nov 29, 2015
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Yes, I'm aware of that, and so the electron should flow like this? Am I correct?

This is why I was confused on the light dimmer picture in the first place, as (in my understanding) the electron flow path would be:
Am I correct in this?

Mar 30, 2015
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Yes.

5. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,066
There is no "first" or "second" in a series circuit at any useful time scale. In a series circuit, the current appears everywhere at the same instant!

After there is current, you can worry about its direction...

Nov 29, 2015
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Hmm, ok, so the order doesn't matter for the "open loop circuit", so what is the difference of the open and closed loop? Is there a topic on AAC that covers this? (searched about it before and with google too but no luck)

Oh! Don't know that before, what I just knew was that each will have the same number of current, but I had no idea if the current appears in this or that time. My former thought was that current also flows through the circuit (hence the confusion) which is terribly wrong!

Thank you for clearing that up!

7. ### dl324 Distinguished Member

Mar 30, 2015
3,376
651
Closing the loop can also be thought of as completing the circuit. Current can't flow unless there is a path for it to flow.

In the circuit you referenced, there's a loop with the diode and one without; and no (indicated) provision for the light to be off.