Matching: 1. Insulator 2. Positive 3. Ion 4. Negative 5. Conductor 6. Electricity A. The charge that attracts electrons. B. An atom with a different number of electrons than protons. C. A material that allows the flow of electricity. D. The caused by the flow of electrons. E. The charge that attracts protons. F. A material that resists electricity.

Conductors and Insulators Conductivity is the ability or power to conduct or transmit heat, electricity, or sound. Conductors are materials that electricity easily passes through, that do not resist the flow of electricity. Examples are copper, aluminum, steel, silver, gold, electrolytes. Not all materials conduct electricity equally well. Conductors: Allow charge to move readily though it.

Insulators : Restrict the movement of the charge Insulators are materials that resist the flow of electricity, so electricity does not easily pass through. Examples are plastic, wood, rubber, cloth, air, glass. Some materials are better electricity insulators than others.

Semi Conductors You can change the behavior of silicon and turn it into a conductor by doping it. In doping, you mix a small amount of an impurity into the silicon crystal giving it Semi-conductor properties. Metals tend to be good conductors of electricity because they usually have "free electrons" that can move easily between atoms, and electricity involves the flow of electrons. Silicon crystals look metallic, they are not, in fact, metals. All of the outer electrons in a silicon crystal are involved in perfect covalent bonds, so they can't move around. A pure silicon crystal is nearly an insulator -- very little electricity will flow through it.

Clockwise from top: A chip, an LED and a transistor are all made from semiconductor material. A diode is the simplest possible semiconductor device. A diode allows current to flow in one direction but not the other.

Magnetic-levitation is an application where superconductors perform extremely well. Transport vehicles such as trains can be made to "float" on strong superconducting magnets, virtually eliminating friction between the train and its tracks. A strong superconductor-derived magnetic field into the body, hydrogen atoms that exist in the body's water and fat molecules are forced to accept energy from the magnetic field. They then release this energy at a frequency that can be detected and displayed graphically by a computer. Magnetic Resonance Imaging (MRI)