# Which conducts electricity

## Simple circuits

#### Conductors and non-conductors

• Metals (iron, copper, gold, platinum)
• coal

Typical electrical Non-conductors (insulators) are:

#### Finer testing with a measuring device

However, light bulbs are only very rough indicators of electricity. Light bulbs only start to glow when there is a certain flow of current, underneath they appear dark, even when current is flowing. However, there are special measuring devices, so-called ammeters, which display even the smallest currents and display the strength of the current on a scale. If you replace the light bulb in the test circuit with an ammeter, you can better decide between conductor and non-conductor. This is particularly useful for studying the conductivity of liquids.

#### Conductors and non-conductors among liquids

Not only solids can conduct electricity, there are also conductors and non-conductors in liquids. However, even conductive liquids generally conduct electricity much worse than metals. Basically acids and bases conduct electricity. Likewise, water mixed with salt conducts electricity. The following applies: The more salt is dissolved in the water, the better the water conducts electricity (see Fig. 2). Since the human body consists to a large extent of water, in which salts are dissolved, your body also conducts electricity. Therefore only experiment with batteries or low-voltage power supplies.

Distilled (salt-free) water and oil, on the other hand, are insulators and do not conduct electricity.

#### Gases normally non-conductors

Gases like the air around you are usually non-conductors (insulators). Electricity can only overcome an "air gap" at very high voltages, which can lead to lightning during a thunderstorm, for example. Some gases can also conduct electricity under special conditions, such as strong negative pressure. In a glow lamp, for example, neon gas conducts electrical current when there is negative pressure, thereby creating a luminous appearance.