The textbook I am currently reading Thermodynamics: An Engineering Approach by Cengel & Boles classifies the energy transferred to a system by an electric heating element as a work interaction instead of a heat transfer interaction.
I have searched for what exactly qualifies as work in thermodynamics and the most satisfying answer that I've found (here) is that an energy transfer is considered a work interaction if it involves a uniform change in the energies of all of the particles of a system by the same amount without changing the shape of the energy distribution of the particles in the system. However, the heating of a system through an electric heating element obviously changes the energy distribution of the particles inside the system as it changes the system's temperature. So why is the heating of a system through the use of an electric heating element considered a work interaction and not a heat transfer?
Best Answer
If you include the heating element is part of your system, then the electrical setup supplying the electrical energy to your system is doing work on your system. If you include the heating element as part of the surroundings, then there is heat being transferred to your system by this part of the surroundings. So it all depends on whether you include the heating element as part of the system or part of the surroundings. In your book's example, the heating element is treated as part of the system.