Eksperimen kali ini datang dari sejumlah e-mail yang datang mendadak, menanyakan tentang menghasilkan listrik dari bermacam buah dan sayuran. Eksperimen ini cukup sering muncul dalam buku ilmu pengetahuan, dan juga salah satu eksperimen yang jarang menghasilkan seperti yang ditulis di buku. Untuk berhasil mencobanya, anda memerlukan:
• Beberapa macam buah-buahan atau sayuran
• Kawat tembaga, klip kertas, kunci atau potongan logam lainnya
• Headphone dari radio, tape, iPOD, dll.
Jika anda mengambil buku tentang eksperimen untuk anak-anak, anda akan menemukan instruksi untuk membuat sebuah baterai dari jeruk lemon atau buah lainnya. Pertama-tama, apa yang sedang anda buat bukanlah sebuah baterai melainkan sebuah sel elektrik. Untuk membuat sebuah baterai, anda akan memerlukan dua atau lebih sel yang saling dihubungkan.
Secara teknis, sebuah 1.5 volt baterai (AA, AAA, C dan D) adalah sebuah sel; 6 atau 9 volt baterai barulah baterai yang sesungguhnya.
Bahkan anda dapat menghitung sendiri berapa sel yang ada di tiap-tiap baterai tersebut.
Tiap sel dari baterai tersebut dapat menghasilkan 1.5 volt. Dua sel yang digabungkan akan menghasilkan 3 volt. Untuk 6 volt, anda memerlukan 4 sel. Untuk 9 volt, anda memerlukan 6 sel. Berapa banyak sel yang anda butuhkan untuk 12 volt baterai mobil (accu)?
Untuk sel saya, saya menggunakan sebuah kentang, tapi anda bisa menggunakan sebuah jeruk lemon, apel, atau buah lain dan sayuran. Anda juga memerlukan 2 obyek yang terbuat dari logam yang berbeda. Saya menggunakan sebuah paku dan sepotong kawat tembaga.
Tancapkan salah satu logam tersebut pada kentang dan tancapkan yang lainnya dengan jarak 1 inchi (2.54cm)
Sekarang anda memiliki 2 potong logam yang berbeda yang dihubungkan lewat cairan dari kentang. Ini membentuk sebuah sel elektrik sederhana, yang menghasilkan kira-kira setengah volt.
Bagaimana anda dapat mengatakan bahwa sel ini benar-benar menghasilkan listrik?
Beberapa buku menyarankan anda untuk menghubungkan sel ini dengan lampu dari senter. Masalahnya, setiap lampu senter, yang pernah saya temui, selalu memerlukan voltage dan ampere yang jauh lebih besar daripada yang dapat anda hasilkan dari sel kentang anda.
Buku lain menyarankan untuk menyentuhkan kedua logam tersebut dengan ujung lidah anda, tapi saya juga tidak pernah berhasil membuat bekerja.
Anda dapat mendeteksi listrik dengan menghubungkan sel tersebut dengan sebuah meter elektrik volt, jika anda memilikinya. Jika anda tidak memilikinya, anda dapat dengan mudah mendeteksi listrik dengan headphone atau sebuah earplug dari radio, CD player, dll.
Jangan khawatir, kita tidak akan merusak headphone tersebut. Jika anda melihat plug dari headphone, anda akan melihat bagian logam yang terdiri dari dua atau tiga bagian.
Pasang headphone tersebut. Sentuhkan salah satu logam dari sel anda ke salah satu bagian logam dari headphone tersebut, kemudian sentuhkan logam lain dari sel anda ke bagian logam lainnya dari headphone.
Jika anda mendengarkan dengan seksama, anda akan mendengar suara "klik" kecil. Jika plug anda terdiri dari 3 bagian, cobalah untuk menyentuhkan bagian lain untuk mendengarkan suara klik tersebut.
Headphone anda bekerja dengan mengubah sinyal elektrik yang lemah dari radio menjadi suara. Listrik dari sell kentang anda menghasilkan suara klik yang anda dengar. Setiap anda menghubungkan dan memutuskan logam dari plug, anda akan mendengar klik. Anda bahkan dapat mencoba buah yang lain dan jenis logam yang lain untuk melihat yang mana menghasilkan suara klik yang keras.
Semakin baik sel yang anda buat, semakin keras bunyi klik yang dihasilkan.
Sumber : http://www.bursainternet.com/Klik-dari-kentang.html
Senin, 31 Mei 2010
Some turtle facts
* The first known turtles existed 200 million years ago.
* There are approximately 300 species of turtles.
* Turtles live on every continent except Antarctica.
* Turtles are cold-blooded. One way they regulate their temperature is by basking.
* Some turtles, such as the Musk turtle, emit an odor when startled.
* Not all turtles and tortoises hibernate.
* The blood of hibernating turtles acts somewhat like antifreeze, allowing it to tolerate cold temperatures.
* Some female turtles produce eggs four years after mating.
* Many species make sound, especially while mating.
* Incubation temperature determines the sex of the hatchling.
* All turtles lay their eggs on land.
* Hatching turtles have an egg tooth at the end of their beak to help open the egg.
* Some land turtles can out run a human.
* The smallest turtle, the Speckled Padloper is 4". The largest is the Leatherback sea turtle, that can
reach up to 10' in length.
* Turtle shells DO break.
* The color and patterns of each species allows them to blend into their natural environment.
* Turtles can regrow bony and keratin tissue.
* Not all turtles have hard shells. For example, Softshell turtles and sea turtles have flexible shells.
* Box turtles are not the only turtles with a hinge to allow part of their shell to move.
* Turtle shells are built into their skeleton.
* The top shell, the carapace, is made up of approximately 50 bones.
* Counting the growth rings on the scutes (scales) of the top shell does not tell the age of the turtle or tortoise.
* Some turtles have hinges on their shells to enable them to close up tightly inside.
* Turtles cannot protrude their tongues from their mouths.
* Aquatic turtles have streamlined shells to help them move through the water. They also have webbing between their toes.
* Aquatic turtles must be in water to eat.
* Tortoises only go to water to drink. They do not swim.
* Some tortoises can dig burrows 45 feet long.
* Many turtles are expert climbers.
* Land turtles ears are sensitive to ground vibration.
* A group of turtles is classically called a bale.
* One of the most common health problems is MBD, Metabolic Bone Disease, caused by improper diet and care.
* All turtles and tortoises do not have the same habitat and nutritional requirements. Therefore, it is very important to research the kind of animal you have or plan to own.
* Turtles have good eyesight, seeing in full color and a strong sense of smell. They have excellent hearing and sense of touch. Their shells have feeling due to nerve endings.
* Instead of teeth, turtles have a sharp beak for eating. Depending on species, the beak may be scissor-like, hook-like, or serrated. The earliest turtles did have teeth and could not retract their head.
* Some turtles can live up to a year without food.
* Tortoises from dry environments have thick scales on the skin to prevent fluid evaporation. Aquatic and semi-aquatic turtles have thinner skin and lack heavy scales.
* Turtles shed their skin in small flakes rather than pieces like other reptiles.
* Sea turtles can swim up to 35 mile per hour.
Sumber : http://www.indianaturtlecare.com/Facts.html
* There are approximately 300 species of turtles.
* Turtles live on every continent except Antarctica.
* Turtles are cold-blooded. One way they regulate their temperature is by basking.
* Some turtles, such as the Musk turtle, emit an odor when startled.
* Not all turtles and tortoises hibernate.
* The blood of hibernating turtles acts somewhat like antifreeze, allowing it to tolerate cold temperatures.
* Some female turtles produce eggs four years after mating.
* Many species make sound, especially while mating.
* Incubation temperature determines the sex of the hatchling.
* All turtles lay their eggs on land.
* Hatching turtles have an egg tooth at the end of their beak to help open the egg.
* Some land turtles can out run a human.
* The smallest turtle, the Speckled Padloper is 4". The largest is the Leatherback sea turtle, that can
reach up to 10' in length.
* Turtle shells DO break.
* The color and patterns of each species allows them to blend into their natural environment.
* Turtles can regrow bony and keratin tissue.
* Not all turtles have hard shells. For example, Softshell turtles and sea turtles have flexible shells.
* Box turtles are not the only turtles with a hinge to allow part of their shell to move.
* Turtle shells are built into their skeleton.
* The top shell, the carapace, is made up of approximately 50 bones.
* Counting the growth rings on the scutes (scales) of the top shell does not tell the age of the turtle or tortoise.
* Some turtles have hinges on their shells to enable them to close up tightly inside.
* Turtles cannot protrude their tongues from their mouths.
* Aquatic turtles have streamlined shells to help them move through the water. They also have webbing between their toes.
* Aquatic turtles must be in water to eat.
* Tortoises only go to water to drink. They do not swim.
* Some tortoises can dig burrows 45 feet long.
* Many turtles are expert climbers.
* Land turtles ears are sensitive to ground vibration.
* A group of turtles is classically called a bale.
* One of the most common health problems is MBD, Metabolic Bone Disease, caused by improper diet and care.
* All turtles and tortoises do not have the same habitat and nutritional requirements. Therefore, it is very important to research the kind of animal you have or plan to own.
* Turtles have good eyesight, seeing in full color and a strong sense of smell. They have excellent hearing and sense of touch. Their shells have feeling due to nerve endings.
* Instead of teeth, turtles have a sharp beak for eating. Depending on species, the beak may be scissor-like, hook-like, or serrated. The earliest turtles did have teeth and could not retract their head.
* Some turtles can live up to a year without food.
* Tortoises from dry environments have thick scales on the skin to prevent fluid evaporation. Aquatic and semi-aquatic turtles have thinner skin and lack heavy scales.
* Turtles shed their skin in small flakes rather than pieces like other reptiles.
* Sea turtles can swim up to 35 mile per hour.
Sumber : http://www.indianaturtlecare.com/Facts.html
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