What does electricity conduct?
Not every substance conducts electricity and some substances conduct electricity better than others. With a small experiment you can test for yourself which materials conduct electricity and which do not.
What you need:
- 9 V battery
- Copper wire
- Lightbulb
What it depends on that a substance conducts electricity
- Whether a substance conducts electricity or not depends on whether there are mobile charge carriers in the material. This can e.g. B. be easily bound electrons (in metals) or ions (salt water).
- The conductivity of a substance is usually indicated with the Greek letter σ (Sigma). The unit is S / m (Siemens per meter). Since the temperature also plays a role in the conductivity, the conductivity is at a temperature of approx. 27 ° C measured.
- Copper has z. B. a conductance of more than 58,000,000 S / m. The higher the number, the better the electricity is conducted.
Substances are divided according to how they conduct electricity
The substances are divided into different groups based on their conductivity, so you can see whether the material conducts electricity well or not.
- The first group are the insulators or non-conductors. Most Plastics and non-metals are among them. These substances hardly or not at all conduct electricity.
- Silicon and germanium are assigned to the group of semiconductors. Semiconductors are mainly found in components of the electronics or cell phones and computers. The conductivity here often depends on external conditions such as temperature, lighting or pressure.
- Almost all metals belong to the group of conductors. Silver conducts electricity best, closely followed by copper.
- Superconductors are the best way to conduct electricity. If the temperature falls below a substance-specific transition temperature, the resistance of the conductor drops to zero. This is achieved with metals, alloys or ceramics, which are extremely cooled.
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How to test whether a substance conducts electricity
You can test a wide variety of materials for their conductivity with a small experiment:
- Take a 9 V battery and connect the negative pole to the light bulb.
- Then attach another wire to the lightbulb and one wire to the positive terminal of the battery.
- You can now place your substance to be examined between these two wire ends.
- If the lamp is on, you know that the fabric conducts the electricity.
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