As for this:
I think the answer is instantly. The switch is opened, Games over.
This was in response to what happens when a light is switched off, and of course the answer given is so wrong on so many levels!
When the light is on, it is because power is delivered in an electrical circuit featured by voltage and current - likely to be direct current in a car or alternating current in a home. When the current is suddenly interrupted because the switch is thrown, electrical pressure builds up at the switch. This pressure is known as voltage. If the current was big enough, the voltage becomes high enough to ionise the surrounding air and cause sparks at the switch contacts.
This is precisely the phenomenon used by older car ignition systems to generate very high voltages from 12-Volt DC electrical systems.
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Context, of my quote, you used in your post above:
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The Energy travels from the source >>> to the load (in one direction)
Okay, I got a simpler question, what if the load is disconnected before the energy gets there, what happens to that energy?
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My response:
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jea48 02-12-2025 at 03:03pm
The Energy travels from the source >>> to the load (in one direction)
Okay, I got a simpler question, what if the load is disconnected before the energy gets there, what happens to that energy?
jea48 response:
It breaks the circuit. No circuit, no energy transfer, flow.
What happens when you flip off a light switch? Light goes off immediately.
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First an Edit. Add this to my response:
mclinnguy Said:
Okay, I got a simpler question, what if the load is disconnected before the energy gets there, what happens to that energy?
Can’t happen... The energy travels at near the speed of light. It’s at the light bulb the instant the contact closure completes the circuit... It’s that Fast!
Open the switch you break the voltage feeding the light bulb. Instantly, no light.
If you believe the electrons are moving back and forth in the wire and the electrons are what makes the light bulb light then you might have to wait quite while for the bulb to light up when you flip the switch on....
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With that out of the way....
Source, 120Vac.
Load, 120V 100W incandescent light bulb.
Simple circuit,
120Vac source, SPST snap switch to disconnect source from load.
Close switch, a completed closed circuit is created.
Instantly EM wave energy flows in one direction >>>, at near the speed of light, from the source and is absorbed by the tungsten filament in the bulb. The energy is not consumed by the filament but rather is converted to to some other form of energy. Therein heat and light.
The event can’t happen unless there is a difference of potential, voltage, applied across both ends of tungsten filament in the bulb. Break the circuit, No longer a difference of potential, voltage, applied to the tungsten filament. Game over! No more light.
(I left out the part of the involvement of current, electric fields, and magnetic fields. All are needed to create the energy electromagnetic wave. Just trying to simplify the process.)
I don’t know what kind of lighting you have in, say, above a bathroom vanity in your home. If The light fixture uses incandescent light bulbs just go to the bathroom flip the wall switch on. Light instantly. Flip the switch off. Light’s gone instantly.
Electricity doesn’t work like water in in a garden hose. Water hose, turn off the faucet and water will continue running out of the hose. Electricity don’t work that way.
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As for this:
This is precisely the phenomenon used by older car ignition systems to generate very high voltages from 12-Volt DC electrical systems.
Keeping it simple I’ll use a vehicles back when the electrical system, battery, was 6Vdc.
A high voltage coil is what stepped up 6Vdc to a high voltage for the spark plugs.I can’t remember how many thousands of volts it was back then.
The coil was, to me, a step up autotransformer. IF 6VDC was directly connected to the 6V pos and neg terminals on the coil it would work like an inductor. Not a transformer. A transformer only works when connected to an AC source. OR a pulsating DC voltage. So if you took the battery lead that feeds the neg terminal on the coil and momentarily touched it to the neg terminal on the coil, (completing the circuit), then remove the lead, (breaking the circuit) a high voltage would be induced on the high voltage winding. Electromagnet induction...
And that is the basics of how it works.
Of course for the ignition system of the vehicle there is a lot more to it. The thing that’s used to pulsate, make - and - break the 6Vdc to the coil primary winding is a spring loaded open and close set of "Points", contacts. A Condenser is wired across the set of contacts to extend the life of the contacts. There is a shaft on the distributor that is mechanically driven by the engine camshaft. It’s all about Timing! The distributor shaft has lobs on it that open and close the Points. There is a lot more to what goes on, but I’ll stop here...
@rodman99999 What would the high voltage output of the coil look like on a engine diagnostic scope? Example... A choppy, say, the top half of an AC sine wave? Never really thought about it...
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