Top Banner
Eksperimen sains: 1. Pengukuran viskositas cairan (exp: oli), caranya: Hitung waktu yang diperlukan sebuah bola dengan diameter tertentu untuk bisa tercelup / bergerak dalam cairan. Ujung mulai dan ujung berhenti bisa dipakai sensor cahaya untuk detektor mulai dan berhentinya. Ukur perbedaan kecepatan (perlambatan) ketika sebuah baling2 yang berputar dengan kecepatan konstan dicelupkan dalam cairan. 3. Percobaan Elektrolisa, caranya: Pakai diagram percobaan elektrolisa di buku kimia. Coba pada berbagai larutan seperti air garam dengan konsentrasi yang diukur, pada larutan sabun, air got, air bisaa, dll Catat perubahan yang terjadi pada larutan dan reaksikan gas yang dihasilkan dengan bara api atau tes bau. Ubah2lah arus yang melewatinya. Buatlah koloid logam dengan busur bredig, coba berbagai larutan medianya seperti ar garam, cuka, air bisaa. Buat semua logam dengan arus yang kuat. Coba reaksikan koloid logamnya dengan pembakaran. Sebagian logam dibiarkan supaya teroksidasi jadi logam oksida, lihatlah bentuk kristalnya paa mikroskop. Buat permainan elektrroforesa. Buatlah pipa atau selang L yang mana pada sisi tegaknya dapat dimasuki batang karbon yang diambil dari batang karbon dalam baterai kering (baterai AA 1,5 V dihancurkan dan diambil batang tengahnya). Hubungkan elektrodanya dengan power supply kutub negatif, usahakan batang karbon tercelup kedalam air sebanyak-banyaknya. Rekatkan badang pipa L pada tutup wadah usahakan jangan ada kebocoran. Sedangkan batang karbon kedua yang dihubungkan ke positif, ditempelkan langsung ke tutup wadah. Kemudian selang O2 juga direkatkan pada tutup wadah. Setelah semua terekat pada tutup wadah tanpa ada kebocoran, isi wadah dengan air murni kemudian tutupkan tutup wadah ke wadahnya dan nyalakan power supplynya. Simpan gas yang keluar pada sebuah balon, setelah terisi penuh dapat digunakan.
27

Eksperimen sains.doc

Apr 16, 2015

Download

Documents

Ilham Akbar
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: Eksperimen sains.doc

Eksperimen sains:

1. Pengukuran viskositas cairan (exp: oli), caranya:

Hitung waktu yang diperlukan sebuah bola dengan diameter tertentu untuk bisa tercelup / bergerak dalam cairan. Ujung mulai dan ujung berhenti bisa dipakai sensor cahaya untuk detektor mulai dan berhentinya.Ukur perbedaan kecepatan (perlambatan) ketika sebuah baling2 yang berputar dengan kecepatan konstan dicelupkan dalam cairan.

3. Percobaan Elektrolisa, caranya:Pakai diagram percobaan elektrolisa di buku kimia. Coba pada berbagai larutan seperti air garam dengan konsentrasi yang diukur, pada larutan sabun, air got, air bisaa, dllCatat perubahan yang terjadi pada larutan dan reaksikan gas yang dihasilkan dengan bara api atau tes bau. Ubah2lah arus yang melewatinya.Buatlah koloid logam dengan busur bredig, coba berbagai larutan medianya seperti ar garam, cuka, air bisaa. Buat semua logam dengan arus yang kuat. Coba reaksikan koloid logamnya dengan pembakaran. Sebagian logam dibiarkan supaya teroksidasi jadi logam oksida, lihatlah bentuk kristalnya paa mikroskop.

Buat permainan elektrroforesa.Buatlah pipa atau selang L yang mana pada sisi tegaknya dapat dimasuki batang karbon yang diambil dari batang karbon dalam baterai kering (baterai AA 1,5 V dihancurkan dan diambil batang tengahnya). Hubungkan elektrodanya dengan power supply kutub negatif, usahakan batang karbon tercelup kedalam air sebanyak-banyaknya. Rekatkan badang pipa L pada tutup wadah usahakan jangan ada kebocoran. Sedangkan batang karbon kedua yang dihubungkan ke positif, ditempelkan langsung ke tutup wadah. Kemudian selang O2 juga direkatkan pada tutup wadah. Setelah semua terekat pada tutup wadah tanpa ada kebocoran, isi wadah dengan air murni kemudian tutupkan tutup wadah ke wadahnya dan nyalakan power supplynya. Simpan gas yang keluar pada sebuah balon,

setelah terisi penuh dapat digunakan.

24. Baterai Sel Air garam/ air soda

Page 2: Eksperimen sains.doc

Apabila 2 buah lempeng logam berbeda (beda potensial logam) dicelupkan /dibatasi oleh zat elektrolit seperti air garam , jus buah, cuka, atau air soda (seperti coca cola) maka pada lempeng logam tersebut muncul tegangan.

Tegangan ini dipakai untuk menyalakan peralatan listrik bertegangan rendah seperti jam dinding, kalkulator atau jam digital. Lempeng logam dapat menggunakan uang-uang logam (eksperimen uang logam mana yg positif dan mana yang negatif dengan mengukur tegangan yang dihasilkan). Dengan menumpuk numpuk uang logam tersebut seperti gambar di bawah maka seperti baterai yang diseri sehingga tegangnnya lebih tinggi. Untuk memperbesar arus dengan jalan memparalelnya. Kertas hisap/kertas biasa/gabus dipakai sebagai sekat elektrolit antara 2 keping koin elektrodanya. Lalu kelebihan kertas/gabus dicelupkan ke zat elektrolitnya sehingga merembes sampai antara 2 koin (pastikan sudah merembes).

HOW IT WORKSIf you place a little hydrochloric acid into a jar of water, the compound starts to break down chemically, producing negative and positive ions. An iron is an electrically charged particle. This process is called ionization, and the acid/water mixture is called electrolyte.Placing a strip of zinc and a strip of copper into the acid/water solution, and connecting the two metal strips with a wire, an electrical current starts to flow between them.The zinc strip starts to dissolve, emitting positive ions. For every positive ion that leaves,the zinc strip leaves behind two electrons. Now, with more electrons the strip has anegative charge. As the positive ions flow through the electrolyte, some collide with the copper strip. This causes electrons to be released from the copper strip. Copper is an excellent conductor, so it releases the electrons easily. The electrons released from the strip become neutralized. The copper now contains fewer electrons and takes on a positive charge. The difference between the negative charge on the zinc strip and positive charge on the copper strip creates an electrical voltage between the two strips. Connecting the two strips with a conductive material, such as a wire, an electric current will flow between them from negative to positive. This device is called an electric cell. Since the electric cell uses electrolyte in a liquid form, it’s called a wet cell. In place of acid/water solution, the kit will use cola or any type of acetic fluid. MAINTENANCEYou will need to refill the fluid and clean the bottom case and metal bars weekly, so check the fluid level and conditions of the bars regularly. The copper and zinc bars also need to be cleaned. The bars will become dark from use. Use the sandpaper to restore them to the original condition. Typical operating time per fill - 100 hours. Besides cola, you can also use salt water, fruit juice, or any other acetic fluid.

7. PH meterCari referensi dan macam-macam bunga yang mudah didapat dan ditanam untuk dijadikan pengukur PH. Buat grafiknya dan buat persamaan. Jadikan hasilnya sebagai referensi untuk pengukuran selanjutnya. Untuk itu juga dibutuhkan alat pengukur PH standart sebagai tolak ukur.

11. Build a real working volcano Now we're going to get a little messy. In this experiment we build a real working volcano. After mixing just the right amount of ingredients together, we'll add the final item to make our volcano 'blow its top' spewing red lava down the sides.

Page 3: Eksperimen sains.doc

a. First we need to create the 'salt dough'. Mix 6 cups flour, 2 cups salt, 4 tablespoons cooking oil, and 2 cups of water in a large bowl. Work the ingredients with your hands until smooth and firm. Add more water to the mixture if needed. b. Stand the soda bottle in the baking pan. Mold the salt dough around the bottle making sure you don't cover up the bottle mouth or drop any dough into the bottle. c.Take your time on this step and build your volcano with as much detail as you like. d. Fill the bottle most of the way with warm water mixed with a little of the red food coloring. e. Put 6 drops of the liquid detergent into the bottle. f. Add 2 tablespoons of baking soda. g. Slowly pour vinegar into the bottle and jump back quick! Notice the red 'lava' that flows out of your volcano. This happens because of the baking soda and vinegar mixture. Mixing baking soda and vinegar produces a chemical reaction (a chemical reaction is a process in which one substance is chemically converted to another - all chemical reactions involve the formation or destruction of bonds between atoms) in which carbon dioxide gas is created - the same gas that bubbles in a real volcano. The gas bubbles build in the bottle, forcing the liquid 'lava' mixture of the bottle and down the sides of your volcano.

12. Plastik Buatan a. aduk ½ cangkir heavy cream atau susu hangat perlahan-lahanb. ketika sudah mulai agak memadat, tambahkan beberapa sendok cuka atau lemon juicec. Terus aduk sampai berubah menjadi seperti gel. d. Lalu dinginkan e. Kemudian cuci dengan air untuk membersihkannya, dan walaahhh jadilah plastik organik. Untuk membuat bentuk cetakan, pada langkah c tuangkan ke cetakan yang diinginkan.

13. Smoke Machines (using dry ice, )Untuk pertunjukan yang memakai laser atau cahaya warna warni, akan sulit terlihat jika ruangan terlalu terang. Oleh karena itu seperti yang sering kita lihat, untuk memperlihatkan jalur sinar diperlukan asap-

asap (smoke), biasanya asap yang digunakan berasal dari dry ice yang dicampur air yang akan menghasilkan asap putih pekat namun tidak mengganggu pernafasan. Dry ice bisa dicari pada toku-toko es krim.

15. Fluorescence

Membuat larutan fluoresensi (berpendar bila dikenai cahaya). Caranya:Rebus 1 lembar daun hijau terserah dalam 50-100ml ethanol/alkohol selama 3-5 menit. Klorofil dari daun akan terlarut dalam alkohol tersebut. Matikan semua lampu atau letakkan pada kerdus gelap yang ada lubang intipnya untu mengintip larutan tersebut. Lalu masukkan sumber cahaya putih (bisa lampu susu/ neon putih/ senter led putih) dan sinari larutan tersebut, maka larutan tersebut akan berpendar merah. Cahaya putih tersebut mengeksitasi elektron dalam klorofil dan klorofil akan membangkitkan energi cahaya dalam panjang gelombang merah. Pelajari lebih lanjut tentang eksitasi cahaya ini yang mungkin suatu saat dapat menggiting saudara mempelajari cara kerja laser cairan.

16. LIQUID EYEGLASS CLEANER AND "ANTI-FOG"

Page 4: Eksperimen sains.doc

This product is a small plastic vial with screw cap, in which a piece of chemically saturated folded felt is packed. When the screw cap is removed, this wet piece of felt extends up and above the top opening of the vial, so that the plastic container serves as an applicator when the screw cap is removed. The product is designed as a quick and easy lens cleaner for eye glasses and to use it, you simply remove the cap, dab the wet felt lightly on each side of the eye glass lens and then polish off with a handkerchief or tissue. It not only cleans the lens with a sparkling clarity but it also retards fogging of the lens under certain conditions of heat and cold. Another feature is its long lasting effect, so convincingly demonstrated by suggesting that the customer or prospect smear a LENZ-BRITE cleaned lens with his finger and then polish off with his handkerchief, without further application of the cleaner. This feature makes one application last all day long. The product is simple to make - all that is needed is your vial which may be plastic or glass, the felt or any absorbent substance that will hold the non-drying cleaning solution and the solution itself. The absorbent substance may be felt, synthetic sponge, cotton wicking, or even a piece of cloth rolled up to fit the small container or dispenser. FORMULA FOR THE SOLUTION: Ethylene Glycol . . . . . . . . 8 partsWetting Agent . . . . . . . . . 1 partWater . . . . . . . . . . . . . 8 parts PROCEDURE:Mix the wetting agent in the water and then stir in the Ethylene Glycol. We have given the units as "PARTS". You may consider the parts as drams, ounces, pints, quarts or gallons according to size batch you wish to make. TREATING THE FELT: As explained previously, other substances may be used in treating any substance with this solution; simply immerse the felt in the solution and allow to remain until it is completely saturated with the liquid. Wring out only lightly and then insert the treated felts in small vials or containers. One concern uses a strip of felt folded and inserted in the vial, so the folded edge protrudes above the opening of the vial, the fold being the point of application to the lens.

Colorful Fire LogsSelect a large log and bore several holes about 1 inch in diameter in the log. Pack each hole withsawdust that has been soaked in a solution of one of the following chemicals. You may combineseveral colors in one log, or have one log for each color. Either way you will have beautifulcolored flames in your campfire. Most of the chemicals will be available at your local grocerystore, hardware store or drug store.

Chemical ColorCalcium Chloride used to melt ice OrangeSodium Chloride (Table Salt) YellowPotassium Nitrate (Salt Peter) VioletCopper Sulfate (bluestone) Blueused to treat disease in cattle feetCream of Tartar VioletBoric Acid Antiseptic Eye Wash (Borox) Green

Fire CubesSeparate the cups of an egg carton by ripping or cutting in between them. Stuff the individual

Page 5: Eksperimen sains.doc

cups with the sawdust soaked in one or more of the chemical solutions. Set the little cups amongthe kindling and watch for the various colors to appear.

Campfire Moth WatchNight-loving moths are more numerous than daylight loving butterflies. There are about 10 timesas many months as butterflies in the world. Not all moths are nocturnal but most are.On a rainless, windless night tie an old white sheet between two trees. Weight the sheet downwith a log or heavy rocks. Shine a light on the sheet. Bait strops of cloth by dipping them intoany of the following substances: brown sugar water, honey, molasses, fruit juice, mashedbananas or peaches.Label or remember what bait you put on the sheet. Every hour quietly visit the sheet to see andrecord any moth activity. Do the moths prefer one bait over another? Have you attracted morethan one variety of moth? Do different species prefer different nectar sources? Try it some nightwithout the light. It might work best for a backyard camp out or campground where you haveelectricity for your night light.Most nocturnal moths use moonlight or other sources of light to navigate in the dark. They areoften attracted to the blue light of a campfire. This light is similar to the moonlight and theconfused moths will often fly around trying to get oriented. In it’s exhaustion it will often fly intothe flames. You can help by brushing it gently away from the fire.Moths you may see around the campfire are: Banded Woolybear, Underwing Moth, Tiger Moth,Giant Silkworm Moths (Luna Moth and Polyphemus Moth.)

Page 6: Eksperimen sains.doc

2. Pengukur indeks bisa medium (refraktometer), caranya:

Seperti yang ada pada buku pelajaran fisika optik:maka perubahan sudut sinar keluar sebanding dengan indeks bias prisma. Kita buat wadah kaca berbentuk prisma yang kemudian medium cairan yang ingin kita ukur kita tuangkan pada wadah prisma kaca tersebut. Lalu pergeseran sinar keluarnya kita ukur. Karena penyimpangan sudut keluarnya sangat kecil maka kita pantul-pantulkan terlebih dahulu menggunakan susunan cermin datar sehingga jarak sinar keluar dapat jauh namun alat tetap ringkas. Susunan yang saya ajukan seperti gambar diatas.Kegunaan pengukuran indeks bias antara lain: menentukan jenis zat dilihat dari tabel daftar indeks bias bermacam-macam zat, mengetahui kadar gula dalam larutan, dan lain-lain.

3. PolarimeterBekerja berdasarkan prinsip polarisasi. Polarisator seperti saringan cahaya, cahaya yang nampak kita lihat memiliki banyak arah getar, polarisator hanya bisa meneruskan satu arah getar saja. Apabila 2 polarisator dipasang paralel searah maka cahaya dapat diteruskan namun bila satu polarisator diputar sudutnya maka intensitas yang keluar akan semakin berkurang sebanding dengan sudut putarannya.

Aplikasinya adalah jika kita meletakkan larutan gula dengan konsentrasi tertentu diantara 2 polarisator maka larutan gula ini dapat mengubah sudut arah cahaya yang datang sehingga semisalnya saja larutan gula diletakkan pada polarisator 1 dan 2, karena arah getar jadi berubah sudutnya maka sinar yang masuk ke polarisator 2 tidak lagi tegak vertikal sempurna namun agak sedikit bersudut sehingga cahaya yang keluar dari polarisator 2 tidak berintensitas maksimum lagi. Dengan mengukur pelemahan intensitas ini atau sudut perubahan arah getarnya(dengan memutar polarisator 2 sampai sudut dimana intensitasnya maksimum) maka bisa didapat konsentrasi gula yang diukur.

Page 7: Eksperimen sains.doc

POLARISATOR SEDERHANA dapat ditemukan pada belakang LCD kalkulator bekas berupa lembaran plastik tebal yang ditutupi aluminium foil. Kupas aluminium foilnya dan perlahan-lahan dengan silet ambil lembaran plastiknya yang melapisi kaca LCDnya. Potong jadi 2 dan coba arahkan pada cahaya dengan konstruksi diatas, coba putar-putar keduanya, mestinya jika diputar sehinga polarisator 1 tegak lurus polarisator 2 akan gelap, kalo searah akan terang.

8. Cerminmembuat kaca cermin sendiri (lihat modul pembuatan kaca)Kumpulkan macam-macam gelas berbentuk cekung atau cembung bisa dari tutup jam atau kaca spion (cermin ceembung) tinggal dibalik jadi cekung. Lalu perlakukan seperti (a).

9. LCD projector (MEMBUAT SENDIRI LCD PROYEKTOR !!)Yang dinamakan LCD adalah semua layar digital seperti HP maupun kalkulator. Proyek ini membuat layar LCD anda yang kecil untuk diproyeksikan sehingga nampak besar dan dapat dipakai seperti untuk presentasi. Dasar cara kerjanya adalah sebagai berikut, lampu yang kuat menyinari layar LCDnya. Pantulan dari layar LCD ini diteruskan ke lensa proyektor. Atur jarak lensa proyektornya untuk mendapatkan bayangan yang jelas.

Page 8: Eksperimen sains.doc

22. Flashlight Fiber OpticsMake two small holes in the cap of a small mustard jar, diagonally opposite each other. Attach the jar to a flashlight, bottom end of jar against the flashlight lens, using several layers of duct tape. Make sure that the glass walls of the jar are completely covered with tape so that no light comes through the side of the jar. Fill the jar with water and cap it, turn on the flashlight, and turn out the lights. Allow a thin continuous stream of water to pour out of one of the holes in the cap (the other hole allows air into the jar). The light will be captured within the stream due to total internal reflection. The stream will not be visible from the side and the light will only be seen when the stream breaks up or hits something.

4. Mikroskop Teknologi TinggiBuat cahaya pengiluminasi utk mikr fase kontras dengan membuat sinar lurus yang difokuskan oleh lensa cembung dimana cahaya terfokus ditutupi tengahnya sehingga cahayanya berbentuk seperti cincin kecil bukan titik fokus.

Page 9: Eksperimen sains.doc
Page 10: Eksperimen sains.doc

4.1. Mikroskop 3D, prinsipnya bahwa dengan menyinari sample menggunakan warna campuran merah dan cyan (biru muda) maka obyek yang dilihat akan nampak seperti 3 dimensi (seperti pada kacamata 3D yang sempat booming). Meskipun ini hanya tipuan mata tapi sangat menarik untuk dipelajari. Perlu diperhatikan, sumber cahayanya yang berwarna putih seperti lampu neon atau lampu susu atau LED superbright putih.4.2. Mikroskop cahaya pantul. Sampel disinari tidak dari bawah seperti biasanya namun disinari dari atasnya (hendaknya pengaturan jarak sedemikian rupa). Untuk memudahkan penempatan LEDnya bisa memakai kawat tembaga kaku yang dapat dililitkan ke dudukan mikroskop. LED bisa memakai LED Superbright berwarna putih atau gabungan LED RGB (Red Green Blue), usahakan semua superbright. Dengan LED RGB yang tiap LEDnya dapat diatur intensitasnya dengan mengatur besar resistor gesernya (perhatikan gambar rangkaian disebelah mikroskop), maka sample yang disinari dapat dilihat pengaruhnya terhadap warna tertentu (beberapa mikroorganisme hanya nampak bila disinari warna tertentu). Pengaturannya dapat dimodel mikroskop CAHAYA PANTUL atau CAHAYA TEMBUS. Untuk CAHAYA TEMBUS sampel dipotong tipis. Sedangkan mikroskop CAHAYA PANTUL tidak perlu, seperti seranggga atau bahkan mineral batu batuan.4.3. Mikroskop Digital, webcam/camera pada lensa okuler (dekat mata). Mulai dengan mata normal sampai terlihat sample dengan jelas kemudian pasang webcamnya/kamera pada lensa okuler. Sambungkan kamera ke computer dan lihat hasilnya, atur pencahayaan bila perlu. Bila tidak didapatkan bayangan, lakukan:- Geser okuler MENJAUHI obyektif atau geser KEATAS, bukan kebawah. Sehingga bayangan dari obyektif tidak lagi di ruang 1 lensa okuler tapi bergeser ke ruang 2 okuler sehingga didapatkan bayangan dari okuler yang bersifat nyata.-Bila masih belum bisa, Lepaskan lensa okuler dari tabungnya, lalu ganti lensa okulernya dengan kamera. Atur jaraknya.

Page 11: Eksperimen sains.doc

Gambar yang tampil di monitor computer dapat diukur besarnya untuk mengetahui ukuran sample (luasan), dapat dipisah-pisahkan, dapat disimpan gambarnya (capture) dapat dilihat pergerakannya (motion detector), menggunakan software-software pengolah citra (bisa MATLAB, dll).4.4. Mikroskop Proyektor, Seperti mikroskop biasa tapi cahayanya menggunakan laser pointer (semakin kuat semakin baik) bukan pantulan cahaya matahari. Setelah pada okuler ditangkap cahaya, atur okuler dan obyektifnya untuk mendapatkan bayangan yang jelas. Tangkap dengan layar putih atau millimeter untuk menggambar atau mengukur besar samplenya.

14. A Laser X-RayYou can use your laser as a sort of X-ray machine, to examine the inside of a frosted lightbulb. This can be a quick way to check the filament of the bulb. Shine the laser pointer onto the light bulb, and observe it from the opposite side. You will see a clear shadow of the filament, so you can tell if the filament is broken.How does this work? The laser pointer creates a tiny spot of light on the bulb. The frosted coating on the bulb causes this light to spread in all directions. As it crosses the inside of the lightbulb, the filament creates a shadow that appears on the frosted coating on the opposite side of the bulb. Please note that the only reason to use a laser for this is because it produces a small, very bright point of light. Theoretically, you could punch a hole in a piece of cardboard, shine a bright light through it, and hold the lightbulb against the hole while examining it from the other side. A comparison of these two methods might make a nice science fair project.

6. Laser pointerDengan kaca2 buat bentuk 3 dimensi dari laser yang dapat terlihat saat ada asap.aplikasikan ke sistem keamanan dengan satu sensor cahaya diujungnya.Komuikasi modulasi suara dengan pulsa sinar laser, buat juga modulasi frekuensi tertetu (DTMF) dengan laser untuk remote kontrol.

5. Eksperimen tegangan tinggi.Sumber tegangan tinggi yang ada diantaranya: rangkaian raket nyamuk (coba ubah2 nilai kapasitor besarnya), rangkaian flasher kamera (cukup tarik 2 kabel yang ke lampu blitznya saja).Eksperimen dengan trafo2 yang ada dengan input osilator DC (IC555) dengan macam-macam sinyal sinus, spike, kotak, segitiga catat perubahannya.Hati2 jika memakai tegangan 220 Volt, arusnya harus dikurangi dengan resistor hitung dulu hambatan trafo, supaya arusnya sekitar mA saja.

6. Generator Vandegraff buatan sendiri

Page 12: Eksperimen sains.doc

Copper brush dapat digantikan dengan kabel serabut 220 V biasa yang dikumpulkan serabutnya. Copper brush ini dapat dihubungkan ke ground atau sumber tegangan tinggi statis, seperti peralatan yang tidak digrounding (jika menyentuh CPU komputer yang tidak diground kita akan tersetrum, setrum inilah setrum statis). Rubber dapat diganti karet ban atau pita karet terserah yang penting lebar. Bolanya menggunakan bola plastik biasa yang murahan yang keseluruhan ditutupi aluminium foil dan aluminium foil ini dihubungkan dengan copper brush bagian atas.Cara kerjanya sebagai berikut, muatan dari ground mengalir dan terkumpul pada copper brushes bawah. Muatan ini kemudian tersentuh dan terbawa oleh karet yang berputar keatas. Sampai diatas muatan-muatan yang terbawa oleh pita karet ini ditangkap oleh copper brush atas dan dialirkan ke aluminium foil bagian luar bola. Karena proses pengaliran muatan ini berjalan terus menerus dan juga karena muatan statis yang tidak bergerak, maka muatan akan terkumpul semakin banyak pada bola aluminium foil sehingga setelah muatan ini cukup besar, dapat mengeluarkan kilat. Lebih jelas jika dilakukan di ruangan gelap.

18. GENERATOR LISTRIK STATIS MENGGUNAKAN PIPA PVC

Page 13: Eksperimen sains.doc

Dasarnya yaitu dengan menggosok pipa PVC dengan kertas yang terhubung ke ground, maka pada pipa akan muncul muatan listrik statis. Muatan yang terkumpul pada badan pipa PVC dialirkan ke leyden jar (lihat bab selanjutnya) melalui kawat serabut tipis yang berfungsi seperti sikat pengumpul muatan-mutan yang tersebar pada badan pipa PVC. Perlu diperhatikan, yang terhubung ke kawat serabut pengumpul adalah yang elektroda tutup sedangkan yang ke ground adalah elektroda luar.

The choices of static electricity generator designs that are available seem to be either that of the simple Electrophorus or something much more complicated, such as the Wimshurst machine or the Van de Graaff generator which involve mechanical rotators, motors, belts, pulleys etc. This generator is extremely simple to make, but fills in much of the huge performance gap that exists between the Electrophorus and the Wimshurst machines etc. The generator is made by using a piece of 3/4 inch pvc pipe about four feet long and a piece of cotton fabric. Paper seems to work quite well also. To operate, one simply holds the fabric or paper with the left hand wrapped around the pipe. The pipe is then pushed and pulled through the fabric, with large strokes, while holding the pipe near some fine wire tip pickups to collect the charge. The wire tip pickups can be connected to a leyden jar or electrostatic motor etc. It is also a good idea to hold in the left hand, along with the fabric, a piece of metal that is connected to ground. This gives the generator a good voltage reference point and keeps the body from building up a big charge that will zap you the next time you touch a grounded object.

With the spark gap set at about 1/4 inch, a spark can be produced across it with almost every stroke of the pipe. This PVC pipe generator does a very good job of running an electrostatic motor like the one described. This generator worked well for me even on a very wet rainy day.

19. Film Can Capacitor (Leyden Jar).TABUNG KAPASITOR ELEKTROSTATIK (LEYDEN JAR)Generator elektrostatik (semisal vandegraff) butuh tempat untuk menampung listrik statis yang dihasilkannya. Dengan menampung listrik tersebut, kilatan yang dihasilkan dapat lebih besar seperti pada gambar dibawah dimana kilatan mudah nampak. Cara membuatnya, pada bagian dalam tabung dilapisi dengan aluminium foil, lalu hubungkan dengan elektroda tutupnya. Kemudian buat juga lapisan aluminium foil diluar tabung dan hubungkan dengan kawat tembaga. Hubungkan kawat tembaga dan elektroda tutup pada generator elektrostatik (atau sentuhkan elektroda tutup pada bahan yang menghasilkan listrik statis seperti balon digosok di baju, pipa PVC digosok kain wol, dll) untuk menyimpan muatan listriknya. Setelah beberapa saat, coba dekatkan kawat tembaga penghubung foil

Page 14: Eksperimen sains.doc

luar dengan elektroda tutup penghubung foil dalam, hati hati tegangan tinggi lakukan dengan memakai kaus tangan. The electrostatic generator needs a place to store and build up an electric charge. Without the capacitor, a static generator such as the one made with PVC pipe would have to be operated in a very dark room in order to see any sparks produced. The capacitor stores up enough of a charge to make a very visible spark in broad daylight and, can also be heard.

The picture of the film can leyden jar is self explanatory. Now days, a film "can" is really plastic but it is a kind of plastic that makes a great capacitor. The inside foil can be taped to the wall or secured any way you want, so long as it makes good contact with the wall. One person wrote back and reported that the film can exploded as a result of using rubber cement to glue the inside foil to the wall. Rubber cement is highly flammable and explosive and was set off by sparking inside.

23. A STACTIC ELECTRICITY GENERATOR.MATERIALS...- A LAUNDRY DETERGENT BOTTLE- A COAT HANGER- ONE BOARD THAT IS LONGER THAN THE DETERGENT BOTTLE- TWO BOARDS THAT ARE THE SAME SIZE THAT ARE SMALLER THAN THE LONG BOARD- A SIX INCH PVC PIPE- A STOOL- TWO DOWELS THE SAME SIZE ABOUT 2 INCHES TALL

FIRST OF ALL NAIL THE TWO SMALL BOARDS TO THE END OF THE LONG BOARD. THENYOU DRILL A HOLE THROUGH THE TWO SMALL BOARDS. THEN YOU MAKE A HOLE INTHE BOTOM AND TOP OF THE DETERGENT BOTLE .THEN BEND THE COAT HANGER SO IT MAKES IT LOOK LIKE THIS |____________ ___ THEN YOU STICK IT INTO THE HOLES

YOU MADE IN THE BOTTLE AND GLUE THEM SO THEY'RE SNUG. WHILE IT IS DRYINGYOU MIGHT WANT TO SCREW THE TWO DOWELS TO THE SIDE OF THE PVC PIPE ANDTHEN SCREW THEM ONTO THE BOARD. AFTER THAT YOU WOULD WANT TO COVER THE PVCPIPE WITH TIN FOIL BUT LEAVE ONE END RIPPLY, THEN PUT THE BOTTLE IN ANDBEND THE TIN FOIL SO IT JUT BARLEY TOUCHES.THEN STAND ON THE STOOL,TURNTHE CRANK AND TOUCH THE FOIL.

20. KAPASITOR VARIABEL MENGGUNAKAN BAKING SODA

Page 15: Eksperimen sains.doc

Kapasitor variabel menggunakan baking soda. 2 lembar aluminium foil digunakan sebagai elektroda. Kedua elektroda ini dicelupkan dalam larutan baking soda. Kemudian ukur kapasitansinya. Cobalah untuk membuat eksperimen untuk mencari hubungan antara dosis banyaknya bakingsoda dengan besar kapasitansi yang terukur.Dengan membuat kapasitor ini, maka kita bisa membuat rangkaian-rangkaian yang membutuhkan kapasitor dengan kapasitas besar tanpa perlu membeli kapasitor berkapasitas besar di pasaran yang harganya sangat mahal. Contoh rangkaian yang membutuhkan kapasitor besar seperti lampu kilat (lampu blitz), magnetic gun atau timer. Untuk rangkaian osilator menggunakan kapasitor ini dapat dilihat pada gambar di bawah.Variable capacitor is controling the frequency of a relaxation oscillator. With a circuit built around a 555 timer, it was easy to get a continuously variable range of 20hz to 100khz, a ratio of 5000 to 1. Typical capacitance range from the piece of aluminum in the above picture is from 10 uf to .002uf. While experimenting with the borax rectifier, I found that everything also worked well using a baking soda solution (1 tablespoon baking soda to 2 cups of tap water). The aluminum strip shown in the above picture was cut from a piece of aluminum pie plate. I also discovered, with either the borax or baking soda rectifier, that it acted like a large capacitor as well as a rectifier when bisaed in the reverse direction. I had built a homemade electrolytic capacitor. I decided to do some experimenting and measurements to see what capacitance values could be obtained. I found it easy to get large values up to 100 uf. Since the capacitance is based on a thin film of aluminum oxide that forms on the aluminum plate, the capacitance can be varied by sliding the plate in or out of the baking soda soda solution. By using a wedge shaped piece of aluminum, I was able to get continuously variable capacitance ranges of up to 5000 to 1. This capacitor of course must be used, as with any electrolytic capacitor, with a positive DC bisa on the aluminum plate. Although one would not expect great leakage specs from this capacitor, I found it to be quite useful in practical situations such as for controlling the frequency of a very wide range relaxation oscillator. As far as I know, nothing like this has ever been available or even manufactured. most variable capacitors are the type used for tuning radios and they rarly have capacitance values above 365 pf and their ratio of variation is not much better than ten to one. We are able to make here a variable capacitor with a capacitance variation range of 5000 to one and with max values of 10 uf or more. The schematics below show different types of relaxation oscillators with their frequency determined by the value of the variable electrolytic capacitor. One is based on the 555 timer chip. Another is based on a UJT transistor. The choice of circuit is based merely on parts availibility although it is easier to obtain a wider frequency range with the 555. For those who are really adventurous, a zinc negative resistance relaxation oscillator can be built and is also shown (see Zinc Negative Resistance Oscillator). The capacitor is easily made by putting two electrodes into a solution of baking soda. One electrode must be aluminum but the other can be just about anything that conducts electricity such as lead, steel, stainless steel or even carbon. In the picture above, a piece of stainless steel sheet is used for the electrode opposite the aluminum. Both electrodes can be aluminum if you want to make a capacitor capable of working with ac voltages. The electrode opposite the aluminum is kept immersed into the solution while the aluminum electrode is moved in and out of the solution to vary the capacitance. When the aluminum is first dipped into the solution, it causes a short to ground through the solution. To form the capacitor, the aluminum plate is connected to a positive supply (S1 in the case of the 555 circuit) through a 470 ohm resistor. The aluminum plate should at this time be dipped most of the way into the solution and swished around for about 20 seconds while a thin film of aluminum oxide forms on it. The aluminum plate becomes the positive side of the capacitor. The

Page 16: Eksperimen sains.doc

aluminum strip is then switched back to the oscillator circuit (using S1). S1 is omitted in the UJT and negative resistance circuits for clarity but the requirements for forming the capacitance are the same as with the 555 circuit. The oscillator is most likely to start running when the aluminum strip is dipped a very short distance into the liquid. The frequency may be out of hearing range and you may need a scope to determine if it is running. The frequency will get lower as the strip is dipped farther into the solution until the leakage becomes great enough to make the oscillator stop. As the aluminum strip is repeatedly dipped in and out, the capacitance and frequency range seem to improve until the strip can be dipped almost its entire length creating the greatest frequency variation range. With the 555 circuit, I was able to make continuous frequency sweeps from 10hz to 100khz. If the electrode opposite the aluminum is slid in or out of the solution, very little effect on frequency is noticed. This shows that the capacitance is happening at the aluminum electrode (strip).

Wide frequency range oscillators with homemade variable capacitor.

Three different relaxation oscillator circuits capable of very wide frequency variations when connected to the homemade variable electrolytic capacitor. For the really adventurous, a zinc negative resistance circuit is also shown.

21. Simple Homemade Thermistor and Pressure Sensor.

Page 17: Eksperimen sains.doc

A thermistor can be easily made using copper oxide. Two clean copper wires were mounted on a board as shown in the picture above. One or both of the wires were heated red hot in a propane torch while separated. After cooling the wires were adjusted so that they lightly touch. An ohm meter connected between the two wires would measure a high resistance (typically 40 to 100k). Holding a flame under the point where the two oxidized wires touch, can make the resistance fall to 1k or less. After the heat is removed the resistance will rise back to the original high value. This simple homemade device can also be used to sense pressure. Squeezing the two wires gently will make the resistance reading on the ohm meter drop in proportion to the applied pressure. In addition, this device can actually produce a voltage by heating one of the oxidized wires. A volt-ohm meter set to the lowest dc current range will easily show the voltage generated. This can produce more voltage than any thermocouple that I have yet made. A meter set on the lowest dc current range also serves as a very low voltage meter.

17. Homemade Photocell and Setup for Experimentation.

Membuat Sendiri Photocell.

Page 18: Eksperimen sains.doc

Lempeng tembaga terlebih dahulu dibakar sampai berwarna merah menyala untuk beberapa saat kemudian angkat dan biarkan dingin. Lempen tembaga ini akan berwarna kehitaman. Lalu teteskan air garam pekat (kadar garamnya tinggi) sehingga membentuk seperti gumpalan. Perlahan-lahan sentuhkan sebagian gumpalan air tersebut dengan kawat tembaga. Supaya tidak mudah bergeser gunakan malam/lilin/plasticin. Jepit kawat dan lempeng tersebut menggunakan penjepit buaya lalu ukur pada milivolt meter. Karena tegangan yang dihasilkan sangat kecil, maka biasanya keluaran ini

sebagai sensor sehingga perlu dihubungkan ke penguat transistor seperti gambar di bawah.An audio amplifier can be connected in parallel with the meter. This allows photocell action to be evaluated either by watching the meter or by listening to the amp. Light that is fluctuating at an audio rate and striking the photocell will be heard in the amp. This is a copper oxide photocell and is very simple to make using materials found around the house, yet it seems to serve the purpose as well as similar but more complex homemade photocells that I have read about elsewhere. Although this photocell does not produce enough power to charge batteries or run circuits etc, it can be used for things such as a light sensor or as a pickup to hear a sound modulated light beam. Just imagine the thrill of hearing a sound modulated light beam through a homemade photocell. To make this photocell, you simply heat a small area on piece of thin copper sheet, red hot in a propane flame, for a minute or so and let it cool. A photocell can now be formed by putting a drop of strong salt solution on the oxidized copper plate and bringing a piece of clean copper wire in contact with the drop. That is all there is to it. The copper wire can be held in place by attaching it to a small block of wood that sits near the copper plate. The plate is one terminal of the cell and the clean copper wire is the other. All pieces of copper that I tried, such as .006 copper sheet from the craft store or a piece of copper tube, worked well. When this photocell is connected across a volt meter, a small voltage (a few millivolts) will be measured. The copper contact wire on the salt water drop becomes the negative terminal. This voltage can increase 5 to 20 millivolts by just shining a small flashlight on to the drop of salt water. By connecting this homemade photocell to an audio amplifier, audio and even music can be heard from a sound modulated light source. I prefer the use of analog volt meters over digital ones for this kind of experimentation. The analog meter can give you a much faster feedback and better overall interpretation of what is happening. A digital meter can still serve the purpose well but getting a good feel for what is happening can be difficult when all you see is a bunch of changing numbers. I have not found it necessary to remove the top layer of black oxide as is suggested in other articles. Sometimes these homemade photocells actually work best on the black oxide areas. One big advantage of this drop of salt water method, is that the whole copper plate does not have to be rigorously prepard. One small spot of good oxide on the copper plate is all that is necessary to make a good photocell. Most pieces however, have a large percentage of usable area. Numerous drops of salt water can be placed in various locations on the surface of the oxidized copper plate. The best spots can then be found by touching the copper wire to the different drops of salt water. All pieces of copper that I have heat treated work as a photocell but some are better than others. The challenging aspect is not in making the photocell work, but merely in getting optimum performance from it. One photocell that I made could give a whopping 50 mv increase when the light from a small flashlight was directed on to it. I usually work under some fluorescent lights which vary in intensity 120 times a second (upper and lower halves of the 60 Hz power waveform). I can also connect the plate and copper wire to an audio amplifier and listen for 120 cycle hum in the amplifier as I touch the copper wire to the different drops of salt water. The best places are easily recognized by the loudest hum. The photocell action can then be verified by blocking the light and hearing the 120 cycle hum diminish or go away completely. The little amplifiers from Radio Shack that fit in the palm of your hand, work well with these homemade photocells. Finding the best spots for photocell action. While working under fluorescent lights or with a sound modulated LED near by, several drops of salt water can be placed on the oxicized copper sheet. By connecting the photocell to an audio amplifier, the best spots on the copper sheet can be found simply by touching the contact wire to the different drops of salt water. The copper sheet shown could be easily cut into several good photocells after the good spots are found.

Transmitting Sound On A Light Beam and Hearing It With The Homemade Photocell.

Page 19: Eksperimen sains.doc

Top picture is a photocell being used as a pickup for sound modulated light from an LED. Distance can be greatly increased with lenses or by using a sound modulated laser pointer. The middle picture is a diagram of how to produce a sound modulated light using a LED (the very bright 2000 to 5000 mcd output ones work best). The headphone output from a small radio is a good source of audio to transmit on the light beam. The lower picture shows a photocell connected to the amp for hearing sound modulated light.

11. Kapal Lorentz (kapal listrik tanpa motor)

Kapal ini bergerak bekerja berdasarkan hukum tangan kanan Lorentz, dimana jika ada arus I mengalir pada medan magnetik B, maka penghantar arus tersebut akan mengalami gaya sebesar F dengan persamaan F=B.I.L. Kapal ini mengangkut magnet dengan medan magnetik B dan sepasang elektroda yang dicelupkan ke air (harus air garam elektrolit) sebatas garis bergelombang. Digambarkan berikut:

Sesuai tangan kanan lorentz, gaya ini dapat menggerakkan kapal tanpa perlu motor dan dihasilkan pergerakan yang halus tanpa riak.

Page 20: Eksperimen sains.doc

12. Electromagnetic Gun

Atau Menggunakan rangkaian flash (lampu blitz) kamera. Rangkaian ini mampu menghasilkan loncatan tegangan yang sangat tinggi dalam waktu singkat. Caranya:

-- Ambil rangkaian lampu blitz pada kamera, perhatikan mana kabel power supplynya dan mana kabel output yang menuju ke lampu blitz, juga mana saklar pengisian kapasitor (saklar ON) dan mana yang saklar discharge kapasitor (start blitz). --Buatlah gulungan kawat berenamel pada sebuah pipa kecil plastik seperti casing bulpen. Batasi ujung-ujungnya dengan baut plastik atau baut besi dilapis plastik atau lem plastik dulu. Caranya buat gulungansampai penuh dengan rata pada satu lapisan. Setelah satu lapisan selesai lapis dengan

Page 21: Eksperimen sains.doc

isolasi lalu mulai gulungan lapisan kedua dan terus begitu sampai kira-kira 10 lapisan. Semakin banyak semakin baik. Lapisan terakhir jangan lupa membungkusnya dengan isolasi, supaya erat bisa dilem plastik. Isi casing bulpen dengan peluru dari besi. --Hubungkan kedua kawat gulungan tadi ke output rangkaian lampu blitz.--Nyalakan rangkaian, tunggu sampai LED tanda kapasitor penuh menyala, baru kemudian saklar discharge kapasitor ditekan. Dan BUUUMMM peluru akan melesat keluar.--Bila belum berhasil atau peluru lemah, coba perbesar tegangan supply atau tambahkan lilitannya. Seperti gambar diatas (figure2)

13. Electromagnetic Rail GunTeorinya sama dengan hukum tangan kanan lorentz seperti digambarkan berikut :

Jika kedua penghantar dibuat cukup panjang beberapa puluh cm, maka peluru akan mengalami percepatan yang cukup tinggi sehingga didapatkan kecepatan akhir peluru sebesar : Vt=((2.F.L)/Mpeluru)^-1/2 dimana F=B.I.L. (B=kuat medan magnet, I= arus, L=panjang rail). Desain ini dapat juga dimodifikasi dengan menambah magnet permanen yang kuat untuk menimbulkan percepatan awal lebih besar, digambarkan berikut:

Disini pada pangkal rail, peluru diberi medan yang arahnya vertikal yang membantu memperkuat medan magnetik yang dihasilkan rail.