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Conductors and Insulators: Electrical Properties of substance All the substances shows specific characteristic with electricity. Some substances allows the electricity to pass through it and some not allows to pass through it; Both the properties of the substances are very useful in electricity. On the basis of these properties all the substances has been categorized in to groups. In this unit we will learn about the substances and their property towards electricity. All substance available around us are made of tiny part called molecules. These molecules are made of smaller tiny parts called atoms. To understand concept of conductor, insulator or electricity it is very necessary to understand the “Atom”. Atom Before we can understand conductor, insulator or electricity we have to know some things about atoms. Each Atom is comprised of three main particles Protons, which are positively-charged; Electrons, which are negativelycharged, and ● Neutrons, which have no charge. ● ● At the core of all atoms is the nucleus. The nucleus contains one or more protons and may also contain neutrons. Orbiting around the nucleus is one or more electrons. Electrons have a negative charge and are very small compared to protons and neutrons. The nucleus is very heavy compared to its electrons. The hydrogen atom is the simplest of all atoms. The hydrogen atom has one proton and one electron. A hydrogen proton has a mass of approximately 1850 times the mass its an electron. Elements are classified by the number of protons they have. This is the atomic number. This is what differentiates the basic elements. For example, ● ● ● ● If an atom has one proton then its a hydrogen atom, If an atom has two protons then its a helium atom and An atom with three protons would be lithium. Copper has twenty nine protons. 1 Conductors and Insulators: Electrical Properties of substance Normally an atom has the same number of electrons as it has protons. When the number of electrons equals the number of protons the atom's total electrical charge is balanced or neutralized. Ion If the atom loses an electron it has more protons than electrons and therefore it’s total charge is positive. If the atom gains an extra electron it contains more electrons than protons and has an overall negative electrical charge. When an atom has an imbalance of electrons and protons it is said to be ionized. ● ● An atom with a positive charge is a called a positive ion. An atom with a negative charge is called negative ion. A positive ion will exhibit an electron attraction while a negative ion will try to lose its extra electron. Protons and Electrons follow specific Laws of Attraction. Since they have opposite charges, they "attract" to one another. If an Atom has the same number of Protons as Electrons, then the Atom is balanced and stable. The orbiting Electrons remain in their "orbits" as long as nothing upsets the balance. When something upsets this balance, then some of the Electrons become "knocked out" of their "orbits". They are called "Free" Electrons. This unbalanced condition can be caused by rubbing cat's fur on Amber, passing a Wire through a Magnetic Field, or putting two chemicals together (as in a Dry Cell Battery). Conductors Materials which are made up of Atoms whose Electrons are easily frees to move are called "conductive materials" or "Conductors." When an electric Voltage is applied across separate points on the material electrons starts moving. Platinum, Gold, and Silver are examples of the very best Conductors of electricity. Gold is used extensively in small quantities for high-value products like: microelectronics, high quality audio components, computer chips, and telecommunications satellites. Copper and Aluminum are also very excellent Conductors of electricity and much less expensive. Almost all Electrical Wiring is Aluminum or Copper, although many actually contain some for added strength. Copper Wires Copper Wire is commonly used on the "customer side" of the Electric Meter. While Copper generally costs more than Aluminum, it is a better 2 Conductors and Insulators: Electrical Properties of substance Conductor, so smaller Wire can be used. Copper also requires less maintenance. Aluminum Wires Aluminum Wire is used as Electrical Conductors on electric utility transmission and distribution systems. The Overhead Wires spanning Utility Poles are made of Aluminum and do not have Insulation around them. Aluminum has two advantages over Copper as a Conductor for Utility Lines: It is lightweight and economical. The light weight permits larger "spans" between Poles. ● Because Aluminum costs less than Copper, it helps Utilities keep costs down. ● Most Electrical Codes do not permit Aluminum Wiring in residential buildings. Aluminum can be used in many commercial and industrial buildings provided it is installed and maintained under strict rules. Insulators A material in which atoms not easily frees electrons from its orbit to move freely even on applying external force, such as applying electric Voltage. Such materials are called “Insulators". Insulators are materials that have structural properties exactly opposite of Conductors. The electrons of Insulator material atoms are not easily "freed." These Electrons are said to be tightly bound to the "nucleus" and are very stable. Due to this high stability of electrons of atoms of Insulator no current flows in the insulating materials. In Electricity the Insulators are used to prevent the flow of electrical current. The rubberized Power Cord and plastic coverings on Appliances are typical examples of Insulators. Glass, rubber, porcelain, and most plastics are good Insulators. In electricity the Conductor and insulators are complementary of each other; the role of insulators is equally important in term of Safety and the conductors provides path for flow of electric current. Q1. Pick Conductors and Insulators 3 Conductors and Insulators: Electrical Properties of substance Safety Pin, Plastic Scale, Wooden Scale, Steel Spoon, Thread, Bamboo stick, Iron Bucket, Plastic Bucket, Steel Glass, Mirror, Rubber Ball, Cricket Bat, Iron Box, Gold Chain, Silver Chain, Iron Chain, Normal Pen, Pencil, Rubber (eraser), Water, Cold Drink. Q2. Write about three main Parts of Atom. Q3. What do you mean by conductive materials or conductors? Q4. What do you mean by Non Conductive materials or Insulators? Make a list of conductive items available at your home. Draw a conductor test diagram Connect cells bulb and wire in open condition connecting with a conductor (Iron Box) Q. bulb will glow or not? 2. As above only replace iron box with pencil. 3. Same circuit any device is connected but bulb is not glowing which type of material is this. 4. Same circuit any device is connected but bulb is glowing which type of material is this. 1. You can try websites: http://www.andythelwell.com/blobz/guide.html http://iq-technologies.net/downloads/index.htm 4 Conductors and Insulators: Electrical Properties of substance Conductor Conductor is the word used to describe any material or substance that allows electricity to travel through it. Almost all conductors are metals, butgraphite, which is what pencil 'lead' is made from, also conducts electricity. Insulator An insulator is a material or substance that does not allow electricity to travel through it. Plastic, rubber, glass and wood are all examples of insulators. 5