If you connect the circuit to an insulator, you will still have an open circuit so the bulb will stay off. Observations and results It may take a bit of work to reverse engineer a flashlight once you have taken it apart.
You should be able to get the flashlight to function without its power switch, however, by connecting the battery compartment directly to the bulb using two wires. Adding a third wire allows you to create a "tester". When you touch a metal object with the free wire ends, the bulb should light up just like it usually would.
This works because the metal objects are conductors, so they create a closed circuit. When you touch insulating materials such as plastic, rubber and wood, the circuit remains open, so the bulb stays off because no current can flow.
Nonmetal conductive materials can be difficult to find. A graphite pencil core may work for some flashlights. But graphite has a very high resistance compared with metals, so the bulb may appear very dim or not light up at all. Cleanup Reassemble your flashlight if you need to use it again or keep your homemade conductivity tester! This activity brought to you in partnership with Science Buddies.
Follow him on Twitter BenFinio. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Go Paperless with Digital. Key concepts Electricity Conductor Insulator Introduction Electricity powers many of the devices you use every day.
Materials Flashlight one you can take apart Batteries for your flashlight Three pieces of wire that can be cut and stripped See Procedure for more information. You might have a junk drawer full of old cell phone chargers—those will work great. You can also purchase wire at hardware or some craft stores. They have many real-life applications.
For example,. To check the temperature of a body, mercury is a common material in the thermometer. Aluminium finds use in the manufacture of foils for food preservation.
It is also used in cooking vessels as it is a good conductor of electricity and heat. Iron is a common material used to conduct heat in vehicle engine manufacturing. The iron plate is composed of steel to briskly absorb heat. In car radiators, conductors find their use in the eradication of heat away from the engine.
The materials or substances that resist or don't allow the current to pass through them are insulators. They are, in general, solid in nature. Often, in a number of systems, insulators are used as they do not allow heat to flow. The resistivity is the property which makes insulators different from conductors.
It is used in motors, generators, transformers, and bush bars. When properly installed, it is the safest and most efficient metal to produce electricity. Copper is commonly used as an effective conductor in household appliances and in electrical equipment in general.
Because of its low cost, most wires are copper-plated. You will often find electromagnet cores normally wrapped with copper wire. Copper is also used in microelectronic conductors, electric circuits and microprocessors because of its high conductivity and low resistance to joule heating.
It is also used in mobile phones, TVs and computers. Aluminum is yet another metal known for its high conductivity of electricity. This makes it a very cost-efficient material, and because of this, it has increasingly replaced copper in some electrical-related applications.
Aluminum is used in long-distance power lines, high voltage electrical transmission and distribution on the utility grid; and, in the service drop, service entrance and building wire feeders. Aluminum, when compared by unit weight, is actually more conductive than copper and costs less. Aluminum material is used in household products or in wiring but it is not a common choice because it has several structural flaws.
For example, aluminum has the tendency to form an electrically resistant oxide surface in electrical connections, which may cause the connection to overheat.
Aluminum is instead used for high-voltage transmission lines such as overhead phone cables which can be encased in steel for additional protection.
Gold is a good electric conductor and does not tarnish like other metals when exposed to the air -- for example, steel or copper may oxidize corrode when in prolonged conduct with oxygen. Gold is especially expensive and is only used for certain materials, such as circuit board components or small electrical connectors.
Some materials may receive gold plating as an electric conductor, or use a small amount of gold which is then platedg in another material to reduce manufacturing costs. Steel is an alloy of iron, which is also a conductor, and is an inflexible metal which is highly corrosive when exposed to air.
It is difficult to cast and is not used in small products or machines; instead, steel is used to encase other conductors or for large structure.
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