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진짜 희한하네요. 

큰 도움 되었습니다.  진짜 희한하네요.

프린스턴에서 나왔던 기사입니다.

https://www.princeton.edu/main/news/archive/S42/72/95S25/index.xml?section=topstories

배터리 방전 반응에서나오는 산물이 내부를 채우면서 점점 bouncier해진다는군요.

They found out it had to do with the way the batteries produce power. Electricity is generated by a chemical reaction inside the batteries as zinc changes to zinc oxide. Initially, a layer of zinc surrounds a brass core in the battery like a donut around a hole. As the battery discharges, the zinc donut gradually changes to zinc oxide.

"The zinc oxide begins to form on the outside and it pushes its way to the core," Steingart said. "As you get more and more zinc oxide, and the zinc oxide begins to appear everywhere in the zinc layer, the battery gets bouncier and bouncier."

오 신기하네요... 도움이 되겠어요..ㅎ