voltage as understood in terms of electric fields explained for circuits

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Noah Adams

Joined Mar 17, 2024
1
Im really wanting to understand voltage more clearly.

I have learned how voltage relates to electrical fields and how its defenition in terms of electrical fields is: the difference in electrical potential energy possesed by an object between two points, divided by the charge of that object

I can understand all concepts related to voltage explained in this forum on khan acedmy
https://www.khanacademy.org/science...ntial-voltage/a/ee-electric-potential-voltage

But i don't understand how voltage as defined in this manner applies to circuits. can anyone explain?
 

Papabravo

Joined Feb 24, 2006
21,256
Im really wanting to understand voltage more clearly.

I have learned how voltage relates to electrical fields and how its defenition in terms of electrical fields is: the difference in electrical potential energy possesed by an object between two points, divided by the charge of that object

I can understand all concepts related to voltage explained in this forum on khan acedmy
https://www.khanacademy.org/science...ntial-voltage/a/ee-electric-potential-voltage

But i don't understand how voltage as defined in this manner applies to circuits. can anyone explain?
So let me get this straight. You understand voltage and potential in the case where there is no method for the charges to move from one place to another, but suddenly when there is a way for this to happen your brain draws a blank. I find that very hard to comprehend.
 

Tonyr1084

Joined Sep 24, 2015
7,943
Welcome to AAC.

Voltage can be best described as "Electric Pressure". The higher the voltage the higher the pressure.
Current is movement of that pressure. Resistance opposes that movement. Current still moves but it moves slower. And the resistor gets warm - or hot, depending on how much pressure and current there is.

Watts is voltage times current. It expresses POWER.

Electric potential is basically a static charge. Not necessarily "Static Electricity" which is developed by buildup of static charges but it IS still a pressure. When the voltage finds a pathway to discharge its energy - that's current. How fast that voltage dissipates depends on the resistance to the flow (current) of electricity.

To understand how voltage works in a circuit you have to consider the current and its pathways. Certain parts of a circuit have a resistance that remains unchanging. So if you have a resistive load such as an incandescent light bulb (which certainly does change its resistance due to heating) the current passing through that bulb will depend on the voltage. Increase the voltage and the current will also increase. And vice versa, lower voltage - lower current.

The light bulb is a poor analogy because it has a cold resistance of some low resistance. But once it begins to glow its resistance goes up quite a bit. That's where "Watts" comes in handy to understand how it's working. A 100W bulb at 120VAC will have a current of (100W ÷ 120VAC) 0.83 amps (of current). That's when it's fully lit. So its "Lit" resistance is 120VAC ÷ 0.83A = 144Ω. Whereas its cold resistance might be somewhere very low, say as a wild guess - 10Ω.
 
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nsaspook

Joined Aug 27, 2009
13,413
Im really wanting to understand voltage more clearly.

I have learned how voltage relates to electrical fields and how its defenition in terms of electrical fields is: the difference in electrical potential energy possesed by an object between two points, divided by the charge of that object

I can understand all concepts related to voltage explained in this forum on khan acedmy
https://www.khanacademy.org/science...ntial-voltage/a/ee-electric-potential-voltage

But i don't understand how voltage as defined in this manner applies to circuits. can anyone explain?
Normally we don't think about or use electrical fields (directly related to energy) in circuit theory.
https://www.fluke.com/en-us/learn/blog/electrical/what-is-voltage
What is potential difference?
Voltage and the term "potential difference" are often used interchangeably. Potential difference might be better defined as the potential energy difference between two points in a circuit. The amount of difference (expressed in volts) determines how much potential energy exists to move electrons from one specific point to another. The quantity identifies how much work, potentially, can be done through the circuit.
 
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