Chapter 11 Electronics and the Computer

Technology Education: Learning By Design

Setting the Scene

Electricity became available less than 100 years ago, but today it is impossible to imagine life without it.

• Electrical signals carry information quickly over wires or through the air via radio waves.
• Electricity is used in the processing and storage of data.
• Electric light has extended our day.
• Electronic entertainment has changed the way we use our free time.

Electronic technology has given birth to the computer- and our current Information Age. In the United States today, there is one computer for about every three people, and 80 million people are Internet users. Worldwide, 200 million people use the Internet. These numbers are continually increasing.

Computers have created an information revolution as significant as the Industrial Revolution of the 1800's. In this chapter, you will learn about the technology that made computers possible.

Electrical Energy

Much of today's technology uses electrical energy. The television, refrigerator and kitchen stove, all types of lights, and your computer all run off the electrical energy supplied to the building. Anything powered by batteries-cell phones, laptop computers, hand-held games- also use a portable form of electricity. Without electricity, much of the technology on which we depend would not be possible.

How does electricity work? How is it stored in batteries? To answer these questions, we need to explore the world of things that cannot be seen.

Atoms- The Smallest Pieces of Our World

The world around you is made up of invisible particles called atoms. An atom is the smallest unit of a material that still has the properties of that material. Take an iron bar, for example. If you keep separating the iron bar into smaller and smaller pieces, the smallest unit that would still have all of the properties of iron is an iron atom. Helium, which is a gas, can be broken down into many identical atoms. Build Your Own Atom

An element, such as helium or iron, is a pure substance that consists of only one type of atom. Other familiar elements are oxygen and nitrogen, which make up the air you breathe, and metals such as gold, nickel, and lead.

Each picture in this periodic table is designed to remind you of the element's name, atomic number, and abbreviation. Point to the element to see its name and number. Click on the element for more explanation and then "Back" to return to the table. There is also an explanation of how to use the pictures as memory pegs. You can also see the name and number of the element by pointing to it and reading the address in the status window at the bottom. At least memorize the first twenty! Each of those first 20 also has a unique color which can also be used for memorizing a list of twenty objects by associating a color with each. http://www.johnpratt.com/atomic/periodic.html 

Protons, Neutrons, and Electrons

As incredibly small as atoms are, they are made up of even smaller particles. Most atoms consist of protons, neutrons, and electrons.

Atoms have a center portion called a nucleus. A nucleus is made up of tiny particles called protons and neutrons. A proton is a positively charged particle. A neutron, which has the same mass as a proton, does not carry any charge.

An electron is a tiny particle that carries a negative charge. In an atom, electrons circle the nucleus very rapidly. The path an electron moves along can be called its "orbit". In most natural atoms, the number of protons equals the number of electrons. The positively charged protons equal the negatively charged electrons. The atom, therefore, has no charge.

Movement of Electrons

Particles with opposite charges are attracted to each other. Particles with the same charges repel, or push each other away. In an atom, electrons are attracted to the nucleus because of the protons' positive charge. Their rapid motion around the nucleus keeps them from falling in it.

In some types of atoms, the electrons are held tightly to the nucleus. These types of materials are called insulators. In an insulator, electrons cannot move freely among atoms. Foam and plastic are examples of insulators.

In other types of materials, electrons can be pulled away from an atom and easily move from one atom to another. Materials whose atoms give up electrons easily are called conductors-i.e., they are able to pass on heat and electricity. Copper wire is a good conductor.

Producing Electrical Current

The movement of electrons is what creates electricity. In copper wire, for example, electrons are so free to move from atom to atom that they actually flow through the wire. The flow of electrons is called current. Electrons can flow through a thin copper wire, through a piece of solid material, or even through the atmosphere, as a lightning bolt.

The unit used to measure the flow of electrical current is an ampere or amp. One amp is equal to about 6 billion billion electrons flowing past a point in one second.

Applying a Force

When you want to move a chair, you have to push on it. You have to exert a force. In the same way, to get current to flow, a force has to be applied. The force that produces a current is called an electromotive force. The unit used to measure electromotive force is called a volt. Just as pushing harder on a chair gets it to move farther, applying a greater voltage produces a larger electrical current.

A battery is one source of electricity. A battery has a positive terminal and a negative terminal. When the terminals are connected by a good conductor, such as a wire, electrons start moving through the wire. They are attracted to the positive terminal and repelled from the negative one. This behavior of electrons sets up a current, or flow of electrons.

Ohm's Law     K=1000       M=.001

An equation called Ohm's Law describes the relationship between current, voltage, and resistance:

Current (amps) = Voltage (volts) / Resistance (ohms)

For a given voltage (force), more current flows through a good conductor than through a poor one. Resistance opposes the flow of current through a material. The unit of resistance, an ohm, is a measure of how well a material conducts electricity. A poor conductor of electricity, such as an insulator, has a high resistance (many ohms). A good conductor has a low resistance (few ohms).

Electronic Components

An electronic component is a device that controls the flow of electricity. Electronic components may make small signals larger, they may limit the amount of current that passes through a device, or they may control the direction of the current. Certain components can also adjust the flow of current depending on the light or temperature. Common electronic components include resistors, capacitors, transistors, and semiconductors.

Resistors

One of the simplest electronic components is the resistor. A resistor controls the flow of current through a circuit. The greater a component's resistance, the less electricity will pass through. Resistors come in a wide range of values, from less than 1 ohm to tens of millions of ohms. One of the most common types of resistors is the light bulb.

Transistors

One of the most important electronic components today is the transistor, which was invented in 1947. A transistor is a type of resistor that lets small amounts of current control the flow of a much larger amount of current. Transistors are used to control electric motors. They can also be used to control the storage of a small electrical charge used to represent information, as in a computer. The transistor is very small. It is a square wafer a few thousandths of an inch on a side. It is packaged in a larger metal or plastic container to make it easy to handle.

Semiconductors

A semiconductor is a material that is neither a good insulator nor a good conductor. The most common semiconductor material is silicon, a nonmetallic element.

One type of component made using semiconductors is the diode. A diode lets current flow in one direction but not the other. It is created when two different materials meet at a junction. A common diode is the LED (light-emitting diode). LED's produce red, green, blue, or white light. LED's are different from ordinary light bulbs. They do not have a wire filament that can break or burn out.

Other Electronic Components

A thermistor has a resistance that changes with the temperature. Thermistors can be used to make electronic thermometers. They can also be used as part of the control system for a refrigerator or oven. A photoresistor has a resistance that changes with the amount of light that hits it. Photoresistors can be used to turn on lights when it gets dark. They can also be used to measure light.

Other types of components are used in building circuits. Capacitors are components that store an electrical charge. Coils store energy in the form of a magnetic field. A battery produces electrical current from a chemical paste that fills the battery. Switches and motors are other examples of capacitors.

Vocabulary:

1)      Ampere: The unit of measurement for electrical current.

2)      Analog Circuit: An electronic circuit that works with analog signals.

3)      Atom: the smallest unit of a material that still has all of the properties of that material.

4)      Battery: A device that converts chemical energy into electrical energy.

Batteries come in all shapes and sizes. They store electrical charge and as we all know when they are put into an electronic device such as a portable radio, they provide the power. The usual battery sizes are seen opposite. These are the type used in school projects and range from 1.5 volts to 9 volts. School projects are powered by batteries because they are safe, easily bought and safe

5)      Bit:  Short for binary digit, bits are represented by a 1 or 0

6)      Capacitor: Components that store an electrical charge.

7)      Circuit: A complete (closed) path through which electricity flows; a connection of electrical or electronic parts or devices used to accomplish some purpose.