Another hazard is the resonance of the magnetron tube itself. If the microwave oven is run without an object to absorb the radiation, a standing wave will form. The energy is reflected back and forth between the tube and the cooking chamber. This may cause the tube to overload and burn out. High reflected power may also cause magnetron arcing, possibly resulting in primary power fuse failure, though such a causal relationship isn't easily established. Thus, dehydrated food, or food wrapped in metal which does not arc, is problematic for overload reasons, without necessarily being a fire hazard.