# Question: Plasma, fluids, and stuff

Keep in mind I have not studied fluid dynamics or plasma stuff at all...

Now, both gases and liquids are fluids. Is a plasma an ionised gas, or an ionised fluid? The reason I ask is because the big difference between the gas and liquid forms of various things is the amount of energy. Is the amount of energy involved the deciding factor of whether something is a plasma or not? If you apply a charge to the neon in a light, it is a plasma. But what if that neon is cooled to liquid, then a charge is applied?

Basically I'm looking for a definition of plasma that covers the difference between liquid and gas.

Thanks.

Related Other Physics Topics News on Phys.org

#### maximus

Keep in mind I have not studied fluid dynamics or plasma stuff at all...

Now, both gases and liquids are fluids. Is a plasma an ionised gas, or an ionised fluid? The reason I ask is because the big difference between the gas and liquid forms of various things is the amount of energy. Is the amount of energy involved the deciding factor of whether something is a plasma or not? If you apply a charge to the neon in a light, it is a plasma.
either way to get it to a plasma state it will climb the phases to its superenergized form, but the correct termonology is ionized gas.

But what if that neon is cooled to liquid, then a charge is applied?
[/B]
i suppose it would energize to the next highest state before plasma, a gas. (depending on how much it is energized)

#### chroot

Staff Emeritus
Gold Member
The reason I ask is because the big difference between the gas and liquid forms of various things is the amount of energy.
No, actually it's not -- the big difference is in strength of the interatomic (intermolecular) forces and the masses of the particles. Any particle of any gas or liquid will have 3/2 kT average thermal energy. If the interatomic forces are small and the particles lightweight (therefore with large thermal velocities), the substance will be a gas. If the interatomic forces are large and the particles massive (therefore with small thermal velocities), the substance will be a liquid. This is the reason that different substances occupy different phases at any given temperature.

- Warren

Last edited:

#### chroot

Staff Emeritus
Gold Member
edit: woops

Excellent, thanks.

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving