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.
Trigeminal neuralgia, a condition that affects the trigeminal nerve which carries sensation from your face to your brain, also causes a sharp shooting pain in head. A sharp, stabbing pain that feels like electric shock around the face is a symptom of trigeminal neuralgia, a nerve disorder that most commonly affects older adults.