Dealing with a touchy subject

This may be a weird question, but here goes. I was given a touch lamp as a gift. All my friends can touch it and it turns on or off, but when I touch it, nothing happens. I can't figure out why. Is it because I have a different amount of static electricity in my body, or what?
-Damien
Touch lamps actually work in a pretty sophisticated way, and static electricity isn't part of the equation.
The underlying concept is called capacitance. A tiny electrical charge is released on to the metal surface of the lamp where it spreads out, filling that surface to capacity with charge. Every object has a different capacity to be filled up with extra charge. The capacitance of a metal desk lamp is very small. When a person touches a lamp, their much larger capacitance is suddenly added to the lamp's.
The lamp's circuitry has to pump out additional charge to fill up, not just the lamp's metal surface, but the human body that's attached to it. The electronics in the lamp sense this sudden increase in flow and trigger a switch that turns the light bulb on or off. When you touch the lamp and nothing happens, either the charge is not flowing from the lamp to your body, or it is flowing but in amounts too tiny to trigger the switch.
This latter situation should occur only when something very small, like a cat or a child, touches the lamp, so we can throw that possibility out. In your case, the problem is probably that your hand is acting as an insulator, not a conductor. Dry, intact skin, with a very small point of contact, like the tip of a finger, offers a very high resistance to electrical flow.
This resistance is even higher if the skin is oily, dirty, dry or thickened. It's like wearing a rubber glove - the electrons just can't flow into you easily. How can you get your touch lamp to work? Try washing your hands, pumicing away your calluses, keeping your skin well moisturised and your touch lamp should work. Or just buy one with a normal switch.
Gary Payinda MD is an emergency medicine consultant in Whangarei.
Have a science, health topic or question you'd like addressed? Email: drpayinda@gmail.com
(This column provides general info and is not a substitute for the medical advice of your doctor.)