ข้อ 5 ENERGY TRANFORMATION ประเด็นการเกิดเสียง (2) Buzzer

http://www.atom.rmutphysics.com/physics/oldfront/98/magnetic1/index5.htm

https://commons.wikimedia.org/wiki/File:Electric_Bell_animation.gif

http://www.explainthatstuff.com/how-electric-doorbells-work.html

http://sciencepo6.wikispaces.com/%E0%B9%81%E0%B8%A1%E0%B9%88%E0%B9%80%E0%B8%AB%E0%B8%A5%E0%B9%87%E0%B8%81%E0%B9%84%E0%B8%9F%E0%B8%9F%E0%B9%89%E0%B8%B2

https://wiki.stjohn.ac.th/groups/poly_electronics/wiki/c1e2f/2.html