0
$\begingroup$

When electrons flow through a circuit, I don't understand how we can hook something up to the circuit (like a bulb or anything else) and have it receive power / do work.

Most tutorials gloss over this detail. What exactly is occurring? Are the electrons literally smacking against something while being pulled through by the electromagnetic force, like water turning a wheel as gravity pulls the molecules down through the solid substance?

How exactly can something move or extract work or generate light or do whatever else when there is a flow of electrons zipping through? What exactly is happening when we hook something up to a circuit? Are electrons flowing through something in particular common to all electronic accessories? What's happening physically / atomically?

$\endgroup$
2
$\begingroup$

Sometimes the electrons do work in a similar way to a fluid (like the water wheel you mentioned). A light bulb, for example, works because the electrons encounter a resistance, and increase the temperature. On a microscopic level, there is a huge torrent of electrons through the material (one amp is on the order of $10^{18}$ electrons per second). The electrons are essentially colliding with nuclei of atoms in the conductor (really they are interacting with the nuclei via the Coulomb force), and these collisions cause the lattice to vibrate and these vibrations are what we call heat. The heat causes the filament to emit light.

Sometimes the electrons do work in a way which is very much unlike the water wheel, because we generally need to reference electric and magnetic fields to understand the circuit, though we did not need to refer to these with the light bulb example (barring the short-range Coulomb interactions). Whereas resistance can be understood by analogy to kinematics, capacitance and inductance cannot, because they rely on force fields, which are simply not a part of kinematics. If it helps, one can can come up with mechanical analogies for the functions of capacitors and inductors (See Hydraulic Analogy), but not their operating principles.

Another important way that electrons do work is the following: whenever electrons are made to accelerate (e.g. by applying a sinusoidally varying voltage across a metal), the electrons emit electromagnetic radiation. Similarly, when electrons absorb electromagnetic radiation, they accelerate. So electrons in one circuit can do work on electrons in another circuit through electromagnetic radiation.

$\endgroup$
0
$\begingroup$

For the light bulb:- Heat is generated when electrons flow through it. Electrons continuously undergo collisions with the kernel or positive particle and these collisions are inelastic. This results in the production of heat. As a result we need to provide external source of energy to maintain the electron flow i.e. to counter the heat loss. When a electrons pass through the bulb filament it gets heated up so much that it gets red hot and starts emitting light.

There are different ways in which electron flow can produce different forms of energy. In the case of motor:- there is an existing magnetic field. When there is a current flowing closed circuit in a magnetic field, the field exerts a torque on the circuit and this makes the motor rotate.

Similarly there are many explanations for the different cases. In a nutshell there needs to be an external source of energy and the electrons are the way in which the energy is transferred

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.