Originally posted by RamnedIf you touch the balloon you're body will act as a ground, I think that's how you say it in english, and the electrons will flow to to you making the attraction weaker weaker till the ballon falls off.
Ok, good. But what leads to the balloon falling: where does the charge go?
Originally posted by RamnedThe wall has an induced positive charge because the negative charge in the balloon pushed away electrons in the wall. Eventually the electrons all move from the balloon into the wall and/or atmosphere and it loses it's charge.
Electric Forces
[b]15. A balloon negatively charged by rubbing clings to a wall. (A) Is the wall positive charged or does it have a negative charge? (B) Why does the balloon eventually fall?[/b]
Originally posted by AThousandYoungThis reflects my intuition on the problem.
The wall has an induced positive charge because the negative charge in the balloon pushed away electrons in the wall. Eventually the electrons all move from the balloon into the wall and/or atmosphere and it loses it's charge.
Both objects here are insulators, which means that any induced charge on them will be immobile and localized (compare this to a conductor, where an induced charge is mobile and spread out over the whole object). The wall itself should be neutral, with small sections of weakly positive and negative charges dotted on its surface.
When you put the negatively charged balloon to the wall, the small regions of weak positive charge on the wall attract it but the electrons aren't able to jump the gap quickly enough to equalize the charges and the balloon stays put. Eventually, the charges will jump the gap in sufficient quantity that the moment of the balloon will overcome the attraction and the balloon falls off the wall.
Originally posted by RamnedNeat. Just interesting to note that guitars get sharper in cold weather because the strings contract, an effect which is not counterbalanced by the drop in air temperature.
You are correct. A rise in temperature will increase the dimensions of the wind instrument much less than it increases the speed of sound in the enclosed air. This effect will raise the resonant frequencies => sharp as temp increases, flat as it decreases.
Next question to follow. Good job. HolyT you have it the same - I misread "tune it lower."
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Originally posted by AThousandYoungyes.
The wall has an induced positive charge because the negative charge in the balloon pushed away electrons in the wall. Eventually the electrons all move from the balloon into the wall and/or atmosphere and it loses it's charge.
I will put up the next question later.
Originally posted by HolyTThis is what's going on. The balloon induces a charge of opposite sign int the wall, causing the balloon and wall to be attracted to each other. The balloon eventually falls because its charge slowly diminishes as it leaks to the ground. (Some of the balloon's charge also could be lost due to positive ions in the surrounding atmosphere, wich would tend to neutralize the enegative charges on the balloon caused by the wall.)
How does the balloon get the excess negative charge to begin with? Thanks.
Ok. 16 to follow.