Archives of Ask A Scientist!
About "Ask A Scientist!"
On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.
Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.
In order for the electrical current inside a transistor to be switched between being on and off, the channel of the transistor must be made from a material whose electrical properties are changed by applying a voltage. For most materials, this doesn't happen. For example, metals like copper allow electrons to flow regardless of how much voltage is applied nearby. Insulators, like window glass or most plastics, don't possess any mobile electrons which can contribute to an electrical current. The best materials for making transistors are called semiconductors, and silicon is one example. Semiconductors are sort of halfway between insulators and good metal conductors. The number of mobile electrons in a semiconductor changes under the influence of small voltages, so that for some values of applied voltage there are electrons present which can flow through the transistor's channel, and for other applied voltages the transistor is insulating.
Silicon is only one out of many different semiconductor materials, and it is not the only one that is used in applications. For instance, a combination of the elements gallium and arsenic forms crystals which permit electrons to move faster than in silicon, so that this material is sometimes used when extreme speed is important. The reason that silicon is used in computers is because it is easier, and therefore less expensive, to make complicated circuits out of silicon than for any other material. Computer circuits require some parts to be made out of insulators in addition to the parts that are semi conducting. With silicon, it is easy to make a good insulator by adding some oxygen to produce silicon oxide. The efficiency with which computer circuits can be made is truly amazing. The average cost is now much less than one penny per 10,000 transistors.
- How does a lens bend light to focus on a point?
- Why is gold such a soft material compared to something like iron?
- How do airplanes fly?
- What is the highest microscope power on an electron microscope?
- Where does water get its strength?
- Why do drops of water cling to glass?
- I know that water can put out a fire. What does liquid nitrogen do to a fire?
- Why are some lights called Halogen Lights? Do they contain elements from the Halogen group?
- When hydrogen explodes and combines with oxygen, where does the energy that is released in the explosion come from?
- What makes gyroscopes in airplanes orient themselves correctly in any position?