Understanding Voltage: How Electrical Energy in EM Waves Powers Devices

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Discussion Overview

The discussion revolves around the nature of electrical energy in the context of electromagnetic (EM) waves and fields, particularly how they interact with devices in electrical circuits. Participants explore theoretical aspects, practical implications, and the underlying physics principles involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question whether electrical energy is in the form of EM waves and how this energy performs work on devices.
  • One participant notes that a changing magnetic field produces an electric field, referencing Maxwell's equations.
  • Another participant suggests that electromagnetic waves propagate energy but primarily serve to transmit signals in circuits, with devices operating through the movement of charges induced by these waves.
  • A participant describes how electromagnetic waves can create voltages across components like transistors, affecting charge movement and current flow.
  • There is a distinction made between EM waves and EM fields, with a claim that while all EM waves are fields, not all EM fields are waves.
  • One participant expresses concern about the clarity of questions posed, suggesting that multiple questions may overwhelm the discussion.

Areas of Agreement / Disagreement

Participants express varying views on the relationship between electrical energy, EM waves, and device operation. There is no consensus on the precise nature of electrical energy in this context, and multiple competing perspectives remain.

Contextual Notes

Some participants indicate uncertainty regarding the quantification of electrical energy as EM waves and the implications of this for circuit functionality. The discussion includes unresolved assumptions about definitions and the nature of fields versus waves.

Who May Find This Useful

This discussion may be of interest to those studying electrical engineering, physics, or anyone curious about the principles of electromagnetism and their applications in technology.

user111_23
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*subject edited*

Is electrical energy in the form of EM waves? If so, how does it do work on a device?
 
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user111_23 said:
where is the E-field when I move a magnet up and down next to an inductor?

A changing magnetic field produces an electric field, according to one of Maxwell's equations.
 
Just curious: are my questions too confusing? If they are, I can simplify them.
 
Maybe pick just the single most important question and avoid the rapid-fire barrage. Many people on this forum could answer anyone of those questions, but all of them together is just tiring.
 
DaleSpam said:
Maybe pick just the single most important question and avoid the rapid-fire barrage. Many people on this forum could answer anyone of those questions, but all of them together is just tiring.

Usually I try to cram many different questions into a single topic. I guess that's a bad idea. :-p
 
user111_23 said:
*subject edited*

Is electrical energy in the form of EM waves? If so, how does it do work on a device?

Electromagnetic waves do contain and propagate energy. However, their main purpose in an electrical circuit is to simply propagate a signal. Most circuit devices work via the use of charges. The electromagnetic wave moves the charges throughout the transmission lines (wires) of a circuit. When these waves meet a device, the charges, currents, and voltages that the wave sets up at the devices is what makes the device work. For example, with a transistor, the electromagnetic wave will create voltages across the gate and drain of the transistor (MOSFET in this case) with respect to the source. These voltages will create fields within the MOSFET and cause the movement of charges creating currents.

I am not sure if you want to quantify the electrical energy of a circuit as being in the form of electromagnetic waves. The waves are energy and they propagate the energy, but what is more relevant is how you measure and interact with the energy as the amount of energy your circuit can get out of these waves can vary.
 
user111_23 said:
Just curious: are my questions too confusing? If they are, I can simplify them.

What's confusing is to change your question in mid-thread by erasing the old one and posting the new one. Now nobody can tell what were the questions that went with the answers.
 
user111_23 said:
Is electrical energy in the form of EM waves? If so, how does it do work on a device?
Electrical energy is in the form of EM fields. All EM waves are fields, but not all EM fields are waves. See: http://hyperphysics.phy-astr.gsu.edu/HBASE/electric/engfie.html#c1

The fields do work because they exert a force (f=q(vxB+E)) on a charge and w=f.d
 

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