Identifying non-electric furnace types: Which one of the following listed furnaces does not use electric power as the primary heating source?

Introduction / Context:
Electric furnaces heat via electrical energy: arcs, induced currents, or resistive elements. Some furnace names refer to geometry or use-case rather than power source; recognizing which are inherently electric avoids design confusion.

Given Data / Assumptions:

• Arc furnace: electric arc between electrodes and bath/charge.
• Induction furnace: eddy currents induced electrically in the charge.
• Resistance furnace: resistive elements convert electricity to heat.
• Pot furnace: traditionally a small refractory-lined vessel heated by fuel flames.

Concept / Approach:
Arc, induction, and resistance are electric by definition. “Pot furnace” is a generic term associated historically with fuel firing (oil/gas) under or around the pot. While an electric pot is possible in modern practice, the conventional classification denotes a fuel-fired unit.

Step-by-Step Solution:

Verification / Alternative check:
Standard furnace catalogs separate electric furnace categories from fuel-fired crucible/pot furnaces.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming “pot” refers to any small furnace; the heating method matters more than geometry.

Final Answer:
Pot