A low DC voltage is produced by the thermocouple when the two junctions are at different temperatures. This voltage is referred to as the thermoelectric voltage. This thermoelectric voltage is produced by the temperature gradient along the thermocouple wires.
Re: What's causes the electric shock type pain in a tooth Hi DM69. I'm not a dentist but I'm pretty sure its the erosion of your tooth exposing the pulp, I had the exact same feeling in my tooth before I had it extracted a month ago, so I feel your pain.
If you feel a mild shock or tingle when touching an appliance, a ground fault in the appliance or improper electrical wiring may be the cause. If you notice a shock after crossing a carpeted surface, it may be from static, which is common in the winter and not cause for concern. You should, however, take other types of electrical shock seriously as you don't want to risk the situation becoming worse.