Electrical Conductors and Insulators Battery Lamp Test terminals

Electrical Conductors and Insulators Battery Lamp Test terminals In this presentation you will: n identify electrical conductors and insulators Next >

Introduction Electrical conductors are materials that allow electric current to flow. Lamp Battery Typical conductive materials include silver, copper, and steel. Test terminals Copper Silver Steel Next >

Introduction Electrical insulators are materials that do not allow electric current to flow. Plastic Typical insulator materials include plastic, wood, and ceramic. Materials have different levels of conduction or insulation. For example, silver and steel are both conductors, but silver is a better conductor. Wood Ceramic Next >

Electrons in Atoms are very close to each other in a solid, so it is quite common for an electron in an outer orbit to move to a neighbor’s outer orbit if there is space. If an electron leaves an outer orbit, it leaves a space behind. - The atom now has an overall positive charge, and it will quickly attract an electron in to fill the space. In some solids, electrons are moving between atoms all the time. + - Next >

Conduction in Solids If a source of electromotive force (EMF), such as a battery, is connected across a solid, all electrons will now be under the influence of an external field. If the field is strong enough, any loosely bound electrons will start to move toward the positive battery terminal. Next >

Conduction in Solids The loosely bound electrons may well be captured by atoms as they pass, but if they are only loosely held, they could be released again. Materials that are classed as good conductors will easily allow the movement of these free electrons. Next >

Question 1 Why is silver a very good electrical conductor? A) It stops electrons from moving between atoms B) It allows electrons to move easily between atoms C) It is shiny Next >

Insulators Resistance is the opposite of conductance. Materials that are good conductors of electricity have a low resistance. Silver Materials that are poor conductors of electricity have a high resistance. Plastic Next >

Insulators If we look at the atomic structure of metals that are good conductors, we see that each has only a single electron in the outermost orbit. In addition, this outer electron is relatively easy to remove. Materials that are good insulators do not have a single free electron in the outermost orbit, therefore, have a high resistance. Conductor - silver Single electron in silver atom structure Insulator - phosphorus Next >

Question 2 Which atomic structure would produce the best insulator? A) C) B) D) Next >

Uses of Conductors and Insulators Conductors are used in applications where we want electricity to flow, for example, in power cables. Insulators are used in applications where we need to be protected from possible contact with electricity, for example, the shielding around cables. Insulator Conductor Next >

Electrocution! Providing a conduction pathway for electricity can be fatal. The human body is made mostly of water and is an electrical conductor, although a poor one. Many people have died by becoming the conduction pathway between an electricity supply and the ground. Next >

Electrocution! Even though air is a poor electrical conductor, if the voltage is high enough, lightning will cause a conduction pathway for electricity to flow to the ground. Some tall buildings have lightning conductors to deliberately channel the electricity safely to the ground. Next >

Question 3 Which of the following items need to be manufactured from electrically insulating material to help prevent electrocution? A) The plug cover on a desk lamp powered by an electrical outlet B) The case of a hair dryer C) The motor cover of a desk fan D) All of the above Next >

Summary In this presentation you have seen: n what makes a material an electrical conductor or insulator n examples of electrical conductors and insulators End >