Science by Email 4 May 2012

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	04 May 2012
News: Micro-wires obey macro law By Patrick Mahony A scanning tunnelling microscope (STM) image of the world's smallest wire. The yellow represents the phosphorus atoms that formed the wire. Scientists from the University of New South Wales led the team that built the world’s smallest wire. In doing so, they showed that an important law of electric circuits, Ohm’s Law, holds true at the atomic level. Electric current can be thought of as tiny charged particles, called electrons, flowing through a material, called a conductor. As electrons pass through a conductor, friction slows them down. In other words, the conductor ‘resists’ the current flowing through it. Voltage is a measure of how much work you would have to do move a charge from one end of the conductor to the other. Ohm’s Law simply states that a voltage (V) equals the current (I) times the resistance (R), or V = I x R. The resistance of most materials stays the same if the current changes, while the voltage varies, meaning most conductors obey Ohm’s Law. Strange things happen to physical laws when you go to the extremely small, or ‘quantum’ level. Electrons start to behave more like waves than little charged particles, and physicists often have to adapt their laws to explain and predict what happens on an atomic scale. Many scientists expected Ohm’s Law to be one of these laws. The scientists made a wire using individual phosphorus atoms. The wire was only four atoms wide and one atom high. What they found was that even this atomic wire obeyed Ohm’s Laws. These scientists are attempting to build a quantum computer, a powerful computer that uses single atoms to perform calculations instead of transistors on silicon chips. Their findings will help them to better understand electricity at a quantum level so they can build such a device. More information Ohm’s law holds down to atomic scale How voltage, current and resistance related Learn more about resistance in this Science by Email activity Careers link Careers in physics
Try this: Finger lock Place your hand flat on the table, palm facing down.   Tap each finger, one at a time.   Curl your middle finger under so that the knuckle rests flat on the table. Try to tap your other fingers.   You will need Your hand Table   What to do Place your hand flat on a bench or desk. Starting with your thumb, lift each finger in turn and tap it on the bench. How easy is it to tap each finger? Bend your middle finger inwards so that the middle knuckle is resting flat on the bench. Repeat step 2 with the remaining fingers. Can you still do it? What’s happening? Your hands may be relatively small, but their anatomy is quite complex. Two types of muscles involved in moving your hands and fingers are extensors and flexors. When an extensor muscle contracts, it straightens a joint, while a flexor muscle bends the joint when it contracts. There are extensors and flexors in your forearm that control the movement of your fingers. To extend and tap your fingers requires the extensor to contract at the same time as the corresponding flexor relaxes. They can’t both contract at the same time. Your thumb, little finger and index finger have their own extensors but your middle and ring finger share the one. When you bend your middle finger, the flexor contracts and the extensor relaxes. Lifting the ring finger requires that same extensor to contract, but it pulls against the contracted flexor and can’t move. Applications The human hand is remarkably dextrous and allows us to perform many tasks that other species can’t, such as using tools. Our thumbs and fingers that allow us to grip and manipulate objects are linked to humans’ high levels of intelligence. A significant portion of the motor cortex (the part of the brain that controls movement) is linked to working the hands. This implies that the evolution of our clever brains and clever hands are linked. Different people have different levels of dexterity in their hands. Most people are right-handed, some are left-handed. Nimble fingers and hands aren’t just good for using tools – they also useful for creative pastimes such as playing musical instruments, writing, painting and typing. By Patrick Mahony Try another Science by Email activity about the human body More information Your wonderful hands View the online version Quiz questions 1. Silica is composed of two chemical elements – what are they? 2. How many Magellanic Clouds are there? 3. What gives leaves their green colour? 4. What unusual piece of equipment did scientists from the University of Glasgow recently use to create pharmaceuticals? 5. What type of marsupial is Burramys parvus? Did you know? Huge volcanic events, known as ‘superplumes’, are thought to be responsible for large iron formations in Australia and North America, according to research from Western Australia. Websites Read it! Have you ever wanted to be an astronaut? Find out what’s involved by reading this article. Watch it! So what actually is a quantum computer? Find out in this video! Events ACT: Big Bang public lecture CSIRO astronomer Dr Lisa Harvey-Smith will deliver a public lecture about the Big Bang, including its history, aftermath and what the latest telescopes might tell us about the fate of the Universe. The lecture will take place at CSIRO Discovery at 6.00 pm, Tuesday 8 May. Following the lecture will be refreshments and the official opening of a new exhibit titled ‘The Big Think – The Big Bang in black and white’. More information can be found on the CSIRO website. FAQs, Saturday 5 May at 9.00 am on Network Ten Why do onions make you cry? How does a microscope work? Is there science in lollies? Why don’t oil and water mix? And what does E = mc2 mean? These and many more frequently asked questions will be answered in this very quizzical episode of SCOPE. Next episodes: Thursday 10 May: How things work Saturday 12 May: Crystals Want to have your own episodes of SCOPE to watch whenever you feel like it? Click here to download them directly into your iTunes folder, or go here to download iTunes. Charges apply. Quiz answers 1. Silica is composed of oxygen and silicon. 2. There are two Magellanic Clouds: the Large and the Small. 3. Leaves get their green colour from a pigment called chlorophyll. 4. Scientists from the University of Glasgow used a 3D printer to create pharmaceuticals. 5. Burramys parvus is the scientific name for the mountain pygmy-possum. Scientists recently moved healthy male pygmy-possums from one population to another in order to increase genetic diversity. Science by Email is a CSIRO publication. The Department of Agriculture, Fisheries and Forestry and bankmecu are proud partners of Science by Email. Editor: Mike McRae | Manage your subscription | FAQ

 

 

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