# How are electrons in a circuit doing work?

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?

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.