Insulators:

When people refuse to pass balls along the line, the line symbolizes an electrical insulator. These substances prevent electric currents from flowing, except in very small quantities under certain situations. Most of the gases are good electrical insulators (as they are poor conductors). Paper, glass, dry wood, and plastics are other illustrations. Pure water is a good electrical insulator, though it conducts some current whenever minerals are dissolved in it. Metal oxides are good insulators; even however the metal in pure form is a good conductor.

An insulating material is at times termed as dielectric. This term occurs from the fact that it remains electric charges separately, preventing the flow of electrons which would equalize a charge difference among two places. Excellent insulating materials can be used to benefit in certain electrical components like capacitors, where it is significant that electrons not be able to flow gradually. Whenever there are two separate areas of electric charge having opposite polarity (known plus and minus, positive and negative, or + and -) which are close to each other but remain apart by an insulating material, that pair of charges is termed as an electric dipole.