In the lecture demo, after the rod touches the tinsel and the tinsel gets charged negative, does the rod become neutral, or does it stay negatively charged ?
No, it doesn’t become neutral. When the rod touches the tinsel, the charge spreads out between the rod and the tinsel (the charges try to get as far away from each other as they can). Some is left on the rod, so the rod remains negatively charged. I’m a bit confused about how induction works… When a charged object approaches a neutral conductor (like an elephant), the like charges flee as far away as they can and the different ones come as close as they can to the charged object. The unlike charges are closer than the like ones, so the unlike ones exert a stronger attractive force than the repulsive force of the like charges (we’ll talk quantitatively about dependence of force on distance in a bit, when we do Coulomb’s Law). So overall there’s an attraction. So, if two objects attract, they could be either two unlike charges, or a charged object and a neutral one – there’s an ambiguity. See also text, p. 548.
Related Questions
- In the lecture demo, after the rod touches the tinsel and the tinsel gets charged negative, does the rod become neutral, or does it stay negatively charged ?
- In the lecture demo with the plexiglass rod, rabbit fur and tinsel, why did the tinsel flare out when charged, as opposed to doing something else?
- How long will the magnets in my mag stay charged? How often should I have it serviced?
