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.
Hyperventilation, or rapid breathing, which can cause tingling in the fingers and around the mouth by lowering the level of carbon dioxide in the blood stream. This is usually associated with an anxious or panicky feeling. Vitamin B-12 is essential to normal nerve function, so low levels of this can cause tingling.