We all know lightning travels through the path of least resistance.
Letâ€™s say we zoom in on the electricity thatâ€™s flowing downwards, and see what it does every 1 nanosecond (it travels about 1 foot in this time period). The flow of electrons gets to a point, and it has to find the path of least resistance to keep going. For simplicity, letâ€™s say it has 1 of 3 options. How does it know which to choose? Clearly, it doesnâ€™t have â€œsensesâ€ to figure this out. If you know your electricity, you know it doesnâ€™t â€œprobeâ€ its different path options until it finds the best way to go. So, how does it know?
A semi-comparable system would be water flowing down a hill. If the water gets to a place where it must choose to go 1 of 3 ways, most of it will go down the steepest path. But some of it will still go down the other two.
Electricity is different. If +10V gets to an intersection, and has to choose between 1 of 3 equally resistive paths (letâ€™s say 250 ohms for the heck of it), one going to +7V, one going to +5V, one going to ground, ALL of the current will go right to ground. Nothing will go down the other two paths. Voltage (potential) difference is just like â€œsteepnessâ€ of a hill in this example.
So, how does it know?
Sander, the problem is that neither your lightning description, nor your analogous “river” scenario, is representative of the system under question. If they were, you would have a valid point.
However, the truth is a bit more subtle than that.
I had to consult with some Electrical Engineer friends to come up with a way to explain this.
The idea that lightning flows downwards from the cloud to the ground, is the problem. What really happens is this: the storm creates a potential difference between the charge of the clouds and the charge of ground. When the potential becomes greater than the resistance of the air, the electrons flow OUT OF GROUND to the cloud. That’s why no electrons end up on either of the other paths (in the circuit example) – they didn’t come from there.
It’s more convenient to think of electricity flowing to ground, but it’s more accurate to describe it as flowing FROM the path of least resistance than DOWN the path of least resistance.
At least, that’s what my sources tell me.
Sote tunajua kwamba umeme husafiri kupitia njia ya upinzani mdogo zaidi. Kwa mfano, unaweza kuona umeme unaoingia kwenye mfumo wa umeme wa umeme, na kuona jinsi unavyofanya kila nanosecond (unasafiri kwa karibu mita moja katika kipindi hiki cha muda). Mtiririko wa elektroni hufikia hatua, na lazima upate njia ya upinzani mdogo ili kuendelea. Kwa urahisi, hebu tuambie kuwa ina chaguzi tatu. Anajuaje ni ipi ya kuchagua? Ni wazi, haina "hisia" ya kujua hili. Kama unajua umeme wako, unajua haijaribu njia zake tofauti mpaka upate njia bora ya kwenda. Kwa hiyo, anajuaje? Mfumo unaolingana na huo ungekuwa maji yanayotiririka chini ya kilima. Kama maji yanakuja mahali ambapo lazima yachague kwenda njia moja kati ya tatu, mengi yatashuka njia ya juu zaidi. Lakini baadhi yake bado itakwenda chini ya nyingine mbili. Umeme ni tofauti. Ikiwa +10V inakuja kwenye makutano, na lazima uchague kati ya njia 1 kati ya 3 zenye upinzani sawa (hebu tuseme ohm 250 kwa heck), moja kwenda +7V, moja kwenda +5V, moja kwenda ardhi, wote wa sasa wataenda moja kwa moja kwenye ardhi. Hakuna kitu kitakachopita kwenye njia nyingine mbili. Voltage (uwezekano) tofauti ni kama tu "upande" wa kilima katika mfano huu. Kwa hiyo, anajuaje? Sander, tatizo ni kwamba wala maelezo yako umeme, wala yako analogous <unk>mto<unk> hali, ni mwakilishi wa mfumo chini ya swali. Kama ndivyo, ungekuwa na sababu nzuri ya kusema hivyo. Hata hivyo, ukweli ni wa hali ya chini zaidi. Ilinibidi nishauriane na marafiki fulani Wahandisi wa Umeme ili kupata njia ya kueleza hili. Wazo la kwamba umeme hutiririka chini kutoka wingu hadi ardhini, ndilo tatizo. Kwa mfano, wakati wa dhoruba, kuna tofauti ya uwezo kati ya malipo ya mawingu na malipo ya ardhi. Wakati uwezo unapoongezeka kuliko upinzani wa hewa, elektroni hutiririka kutoka chini ya ardhi hadi kwenye wingu. Hiyo ni kwa nini hakuna elektroni kuishia juu ya yoyote ya njia nyingine (katika mfano mzunguko) <unk> wao si kuja kutoka huko. Ni rahisi zaidi kufikiria umeme ukitiririka chini, lakini ni sahihi zaidi kuelezea kama mtiririko kutoka kwa njia ya upinzani mdogo kuliko chini ya njia ya upinzani mdogo. Angalau, hivyo ndivyo vyanzo vyangu vinavyoniambia.