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### Course: Electrical engineering>Unit 1

Lesson 1: Getting started

# Voltage

Voltage is a cornerstone concept in electricity. We create an intuitive mental image by comparing voltage to gravity. Created by Willy McAllister.

## Want to join the conversation?

• Wouldn't it be wiser to consider voltage as the difference of potential between 2 nodes? That's how it's taught in Engineering School at least.
• The ski slope isn't a bad analogy for potential. The video makes an analogy between delta height and delta volts. It also implies the concept of ground potential.

IMHO the battery is backwards. There will be an unfortunate road bump when students must come to grips with the convention of current flowing from positive to negative...

Regards,

APD
• From what I am seeing we would only need one battery so why do we have to replace them all the time.
• The chemical inside of them that manages the difference evens out over time making it so there is no diffrence I think.
• I don't like the mountain analogy, water analogy is better, with pressure, since in a circuit voltage doesn't depend that much on the length of the wire, rather on it's resistance, if say we find a wire with zero resistance and we hook it on a 20 volts battery, voltage will be 20 across any two points. Am I right ?
• Hello again Feraru,

There is no such thing as a wire with zero resistance (assuming we avoid superconductors). But even then there would be resistance in the connections to the cryogenic parts.

Both analogies are a good starting point but they leave many questions unanswered especially when you start discussions of capacitors and instructors. In this video I present another way to view the situation. Please let me know what you think:

Regards,

APD
• Is my understanding correct by saying, "one volt is the energy required to move one coulomb of electrical charge", or is it

"One volt is the amount of work one coulomb of electrical charge can potentially do"?

Which one is correct?

Thanks!
• The term "voltage" is the honorary name for "electric potential difference". If it takes 1 joule (J) of work to move a unit charge (1C) between two points in space, then the electric potential difference between those two points is 1 volt (V).

That means 1 volt = 1 joule per coulomb.

If you have to push on the 1C charge to make it move, that means YOU are doing the work (work = force x distance). If you release the 1C charge and it forces its way back to the starting point (like it flows through a circuit), then the CHARGE is doing work.

Here is a formal definition of voltage:
or this revised and improved version: https://spinningnumbers.org/a/electric-potential.html
• So then, according to the mountain analogy, higher the voltage, larger is the amount of work done=> magnitude of the current flowing through the circuit will be large. Am I right?

Your statements are true provided we keep the resistance the same in both circuits.

Regards,

APD
• How is the voltage across a battery different from the voltage across a load?? im thinking it has something to do with power, i.e one supplies power and the other uses power.....ahhh im unsure. If someone could clarify would be much appreciated.
(1 vote)
• There's just one kind of voltage, it's called voltage. It's the number you see if you touch two points in a circuit with a voltmeter. A battery generates a voltage, and yes, it generates power. The term "load" refers to the thing connected to our circuit, the thing that we want to deliver power to. We say a load "dissipates" power. For example, the speaker or the earbud is the load for our radio or music player. In the simplest case, a resistor can be called a load. If we measure the voltage across a load we get a number. That number means the same thing as if we measure across a battery, it's the voltage between those two points.
• I have learned about voltage in other classes but it was never explained this simply. Thank you