a) Semi-conductors: Semiconductor, solid or liquid material, able to conduct electricity at room temperature more readily than an insulator, but less easily than a metal. Such metals as copper, silver, and aluminum are excellent conductors, but such insulators as diamond and glass are very poor conductors .At low temperatures, pure semiconductors behave like insulators. Under higher temperatures or light or with the addition of impurities, however, the conductivity of semiconductors can be increased dramatically, reaching levels that may approach those of metals.
b) Pesticides: a chemical substance used to kill pests, especially insects. The chemical agents called pesticides include herbicides (for weed control), insecticides, and fungicides.
c) Laser: a device that produces and amplifies light. The word laser is an acronym for Light Amplification by Stimulated Emission of Radiation. Laser light is very pure in color, can be extremely intense, and can be directed with great accuracy. Lasers are used in many modern technological devices including bar code readers, compact disc (CD) players, and laser printers. Lasers can generate light beyond the range visible to the human eye, from the infrared through the X-ray range. Masers are similar devices that produce and amplify microwaves.