Zvučna parabolična ogledala (refleksija i fokusiranje zvuka)
Akustično ogledalo je nepokretna sprava koja se koristi za refleksiju i za fokusiranje zvučnih talasa.
ISTORIJAT: Na slici su prikazani metalni reflektori koji su se koristili za demonstraciju refleksije i fokusiranja zvučnih talasa. Oni su se takođe upotrebljavali da kreiraju i fokusiraju toplotne zrake. Aparatura (slika 1) se sastoji od para metalnih paraboličnih reflektora postavljenih na drvene stalke. Jedan od reflektora poseduje mali držač sa kukicom na koju je okačen džepni sat. Demonstrator je koristio ovu spravu da pokaže kako se zvuk kucanja sata može čuti na razmatranom rastojanju, hvatajući zrak koji se projektuje sa određenog rastojanja, a zatim ga ponovo fokusira. Dok satni mehanizam otkucava, prikazana aparatura stvara pritisak talasa u vazduhu, koji se nesputano širi u koncentričnim krugovima. Tokom putovanja talasi brzo gube svoj intenzitet i energija se raspodeljuje u širokom prostoru. Ako ste bili dovoljno blizu sata, vi biste čuli direktno kucanje. Bilo bi potpuno nemoguće čuti sat na udaljenosti od nekoliko metara. O ovom paru ogledala iz Whipple kolekcije se zna veoma malo. Smatra se da su napravljena u Francuskoj ili Nemačkoj tokom prve polovine 19. veka.
Parabolic sound mirrors (reflection and focusing of sound)
An acoustic mirror is an immobile device which is used to reflect and to focus sound waves.
HISTORY: Metal reflectors which were used for demonstration of reflection and focusing of sound waves are shown in the picture. They were also used for creating and focusing of thermal waves. The apparatus (image 1) consists of a pair of metal parabolic reflectors placed onto wooden stands. One of the reflectors has a small holder with a small hook onto which a pocket watch is hung. The demonstrator used this device to show that the sound of the ticking of the clock could be heard at the distance under examination by capturing the ray which projects from certain distance and then focusing it again. While the clockwork is ticking, the displayed apparatus creates pressure of the waves in the air which expands without restraint in concentric circles. During their journey, the waves lose their intensity and the energy gets distributed over a wide area. If you had been close enough to the watch, you would have heard the ticking directly, but it was completely impossible to hear the clock at a few meters’ distance. Little is known about this pair of mirrors from Whipple collection. They are believed to have been made in France or Germany during the first half of the 19th century.