Unit: Energy and Control- Electricity

 The first computer was called ENIAC and was built in the 1940’s by IBM. It was so large that it completely filled a room. Today, the pocket-sized computer organizers have far more computer than ENIAC did. Computers are full of conductors, resistors, and insulators.

Materials:  2 Batteries  Battery Holder  3 wires (2 long 1 short)  1 bulb holder  1 bulb  1 cup of water  Salt  teaspoon

 Connect the short wire from the battery pack to the bulb holder. Connect a long wire to the batter holder only. You now have two free wire ends. Touch the wires together to make sure the bulb lights.  Half-fill a small cup with water. Dip the wire ends into the water but do not let them touch each other. Does the bulb light? Take the wires out of the water.  Add one teaspoon of salt to the water. Stir the water until the salt dissolves. Dip the wires into the water. Does the bulb light? Take the wires out of the water.  Repeat step 4 until something changes

 Draw the circuit  Describe what happened to you circuit as you added more and more salt to the water.  Why do you think this occurred?

 Conductors, resistors, and insulators are materials that control the flow of electricity. Electricity flows easily through a conductor. Conductors are usually metal, such as copper, iron, silver, and aluminum.

 A resistor restricts the flow of electricity. Carbon, like the lead in a pencil, is a good resistor. An insulator prevents the flow of electricity. Glass, plastic, wood, and porcelain are good insulators. Electrical devices make use of conductors, resistors, and insulators so electricity can flow efficiently and safely.

 Pure water cannot conduct electricity. But water with impurities can. The salt that you added to the water was an impurity. As more and more was added, the electricity was able to flow though the salt particles. Eventually your bulb lit up.

 Our lives today are filled with electronic devices. Electronics is a branch of the technology of electricity and makes clever use of conductors, resistors, and insulators. Think about all the electronic devices you have in your home and school. Do you have a television, radio, iP  ad, computer, stereo, or microwave oven? Electronic devices can do many things, such as count, measure, control, remember, make pictures, create sounds, and send signals.

 For a device to be electronic it must contain certain components, including capacitors, resistors, semiconductors, coils, transistors, diodes, and integrated circuits (if you are interested in electronic devices look up the words!). Some of these components behave like switches and control the flow of electricity. Some of them change the size or direction or voltage. Electronic devices control electricity in ways that an be very useful. Therefore, an electronic device uses electricity to control electricity.

 Electronics have come a long way in the last 50 years. The original computers were huge compared to what we use now. The components inside modern electronic devices are extremely small. In fact, a computer “chip,” the size of your thumbnail, can contain thousands of transistors, diodes, resistors, and capacitors.

 How it’s made: circuit boards- 3Sy0 3Sy0