| On the 51 bus on Broadway, a weathered black man asked me, "Is that physics your studying?" "Yeah." "I got a question for you. Is it the wire or is it the animal?" He could probably tell by my face I didn't have a clue what he was talking about. He continued, "When a bird lands on an electric wire, it don't get electrocuted. I mean you'd think we'd see the streets with a buncha dead birds on the ground, but that don't happen. So what I wanna know is is it the wire or is it the animal?" I loved the question, but I had no idea what the answer was and told him so. "Make it your thesis," he suggested. I didn't bother telling him that writing a thesis wasn't necessary for me to pass the class. But I kept the great question in mind. Sure enough, a few weeks later, my physics class talked about getting shocked by electricity. My teacher -- a shaved-headed, former Livermore Lab employee -- told us how voltage doesn't electrocute, a difference in voltage electrocutes. In other words, I can hang off of a 10,000 volt wire and not get shocked, but if I grab onto a 10,000 volt wire in one hand and a 10 volt wire in the other, I'm going to get my pants knocked off!!! So I asked the teacher "Why don't we feel anything when we hold a battery?" After all, a battery has a difference in charges. An AA battery has 1.5 more volts on the negative side than on the positive side. "It's just 1.5 volts, right? It does go through your body but it doesn't feel like much." "What about a 9-volt battery?" Another student asked. "Shouldn't we feel that?" "You can!" Our teacher said. "If you touch it with your tongue, then your saliva can help the current go through your tongue. You don't wanna do that, though. It doesn't feel too good." A weary voice came from the back of the classroom, "Yeah, don't do it." Ultimately, a bird will feel the shock if it has one talon on one wire and the other talon on a wire of different voltage. Is it the bird or the animal? I guess it's neither. It's actually the way electrocution works, or in this case, isn't working. Thanks for the great question, bus guy, whoever and wherever you are! |
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