# Is voltage an abstract concept?

#### fayyaz.nawaz

Joined Mar 10, 2023
1
I am wondering whether Voltage is an abstract concept because we cannot actually measure voltage without the flow of current(even in Voltmeter the deflections is produced due to flow of current only). So if we look at it that way then we can say that Voltage isn't present without current? Also is it possible to have voltage pulse and current pulse sepeartely?

#### Papabravo

Joined Feb 24, 2006
20,621
Voltage is not an abstract concept. You mention deflection which only applies to the now obsolete moving coil voltmeter. Ohm's law is a convenient relationship that mutually relates voltage, current and resistance in a circuit. We also know and can very closely measure the open circuit voltage of a power supply without the need for much in the way of current. I don't think this would be possible if one of the three were abstract and the other two were not.

#### LowQCab

Joined Nov 6, 2012
3,595
The only problem with Electricity is that it's usually invisible.
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#### Papabravo

Joined Feb 24, 2006
20,621
The only problem with Electricity is that it's usually invisible.
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So are electrons, protons and quarks and they are not particularly abstract.

#### BobTPH

Joined Jun 5, 2013
8,136
Yes, voltage is an abstract concept, but not for the reasons you think.

For starters, it is not true that voltage can only be measured by the flow of current. A bridge is a circuit can measure a voltage by finding the point (null) where no current flows.

Voltage is defined as the difference in potential energy due to the electric field. And the electric field is an abstract concept that mathematically simplifies a calculation of forces felt by charges in the presence of other charges.

The only things that are not abstract are the charged particles and the photons that mediate the forces.

#### DickCappels

Joined Aug 21, 2008
10,104
Have you ever used an electrostatic voltmeter or even an electroscope, or for that matter ever rubbed a balloon in your hair?

#### nsaspook

Joined Aug 27, 2009
12,348
EM Fields are not just a abstraction. They are the physical descriptions of reality that exist in the same why that portions of water exist. The mathematical abstraction is what we use to predict the behavior of real things like how EM fields interact with our eyes and skin as electromagnetic wave oscillations of the em field that transmit force, transport energy, momentum and angular momentum across space.

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#### MrChips

Joined Oct 2, 2009
29,861
You don’t have to have current in order to measure voltage.
One of the earliest detectors was a gold leaf electroscope.

#### ronsimpson

Joined Oct 7, 2019
2,797
Help me remember. In Chemistry class we mixed chemicals to make a voltage. In early experiments they had to make a "battery" to get electrons to flow. I cannot remember, but I think a Volt ties back to chemistry.

#### MrChips

Joined Oct 2, 2009
29,861
Help me remember. In Chemistry class we mixed chemicals to make a voltage. In early experiments they had to make a "battery" to get electrons to flow. I cannot remember, but I think a Volt ties back to chemistry.
Yes, you are correct. It is all about chemistry. My sons reminded me that chemistry is physics.

Every metal has a pecking order as listed in the electrochemical series.
For the highest voltage in a battery, you want the two electrodes to be of different material furthest apart on the electrochemical series.

Copper and zinc make a good pair for making batteries.
Gold and lithium make great batteries though rather expensive ones.

#### Janis59

Joined Aug 21, 2017
1,783
Especially good are those cases of electrocutting where someone is getting the REAL shock from IMMAGINARY Voltage? Isnt is so?

#### BobTPH

Joined Jun 5, 2013
8,136
Well, at the fundamental level it is actually the charge distribution that causes electrons to move through his body.

To me it is the same as pressure in a gas. I would call pressure an abstract concept, because what is really happening is molecules are colliding with each other and with the walls of a container, imparting a force.

#### WBahn

Joined Mar 31, 2012
29,521
Help me remember. In Chemistry class we mixed chemicals to make a voltage. In early experiments they had to make a "battery" to get electrons to flow. I cannot remember, but I think a Volt ties back to chemistry.
Early voltage sources were very ad hoc. The first ones were various electrostatic generators and date back into the mid-1600s. These included the Leyden Jar capacitor in the mid-1700s. The battery was first discovered/invented by Volta in about 1800. The discovery of electromagnetic induction came along about three decades later (less than two hundred years ago!).

#### Ya’akov

Joined Jan 27, 2019
8,565
Voltage and current can be seen much like electromagnetism. While we can talk about electric and magnetic fields, they are tied together each giving rise to the other depending on the circumstances.

Rather than thinking of voltage as a thing in and of itself, think of it as an attribute of something that ties it together with current.

As a flawed analogy, but one that makes the point about the facet I am trying to illuminate, consider IP address. The reality is that an IP address, that is something like, 192.168.1.100, is useless on its own. Yet we constantly make practical use of them.

Why are they meaningless? Because unless it is paired with a netmask, there is no way to know which part of the address refers to a network and which to a host. But because that information exists in the routing tables that will be encountered along the way there is no problem just pretending it doesn’t exist.

Similarly, when we talk about voltage we know that any application will necessarily involve a corresponding current. But without knowing the resistance of the circuit we don’t know what current will be associated with any given voltage. We just let that information float and use voltage where is it relevant.

The bottom line is that thinking of voltage as a “thing” is useful, but it’s not “true” in some absolute sense and there is no reason to try to make it so.