Question

Which of these statements best supports the conclusion that a substance is in the plasma phase?

Answer 1

The right answer is D) The substance contains charged particles.

Under the usual conditions, a gaseous medium does not conduct electricity. When this medium is subjected to a weak electric field, a pure gas is considered as a perfect electrical insulator, because it contains almost no free charged particles (electrons or positive ions). But free electrons and positive ions can appear in significant quantities if the gas is subjected to a strong electric field (30 kilovolts / centimeter for air) or at quite high temperatures, if it is bombarded with particles or if is subjected to a very intense electromagnetic field.

When the ionization is large enough that the number of electrons per unit volume is comparable to that of the neutral molecules, the gas becomes a conductive fluid called plasma.

Typically the ionization energy of a body is a few electronvolts. The temperature necessary to form a plasma is therefore the one from which the thermal energy, which can be estimated by the product kT, reaches this order of magnitude, that is to say when kT ≈ 1 eV, ie a temperature about 11,000 K.

Answer 2

A substance is in the plasma phase when there is a mixture of neutral atoms, free electrons and charge ions. If matter at a very high temperature and pressure which typically occur on the sun, the atoms begin to break down, the electrons are stripped from their orbit around the nucleus leaving a positively charged ion behind which can respond to and generates electro-magnetic forces.