The current would go from one finger to the next via the palm. When you wet your fingers, was it the whole hand, or just the finger tips? If the latter, why would that work?
He only had to lick his fingertips. As long as there is a low-resistance path for the current through the skin at the point of contact, it will work. Dry skin has a very high resistance; in contrast, the inside of the body is moist and has a lot of ions to carry current making for a low resistance. You can think of his fingers as a simple loop with three resistances in series that the current has to get through: 1) skin of one fingertip at the point of contact (high resistance), 2) internal path through the inside of fingers and hand (low resistance), and 3) skin of the finger at the other point of contact (high resistance). Since resistance adds up in series, the two high resistances make it impossible for much current to flow. By licking the skin at the points of contact, those two resistances drop and so does the total resistance for the finger to finger loop. Hope this helps!
What an excellent demonstration! Thank you Bob!
Great video. Just as an aside it shows not to be in water when working with electricity.
I have a question. I notice you put the LED on the emitter side of the transistor. What would change if you but the LED on the collector side?
Awesome video thanks!
The current would go from one finger to the next via the palm. When you wet your fingers, was it the whole hand, or just the finger tips?
If the latter, why would that work?
He only had to lick his fingertips. As long as there is a low-resistance path for the current through the skin at the point of contact, it will work. Dry skin has a very high resistance; in contrast, the inside of the body is moist and has a lot of ions to carry current making for a low resistance. You can think of his fingers as a simple loop with three resistances in series that the current has to get through: 1) skin of one fingertip at the point of contact (high resistance), 2) internal path through the inside of fingers and hand (low resistance), and 3) skin of the finger at the other point of contact (high resistance). Since resistance adds up in series, the two high resistances make it impossible for much current to flow. By licking the skin at the points of contact, those two resistances drop and so does the total resistance for the finger to finger loop. Hope this helps!