# Temperature in Kalvins

1. Oct 3, 2005

### gapgirl1010

Liquid Nitrogen vs. Liquid Helium

The reason that liquid nitrogen temperature superconductors are important is that liquid nitrogen costs less than liquid helium. New technologies to store liquid helium have been developed in the last year. This has brought the cost of liquid helium down. how might this affect the direction of the field?

2. Oct 3, 2005

### gapgirl1010

Hi, the absolute zero is -173 right?

This is equal to 0 Kalvins right?
So which is a better superconducter?
Liquid Helium @ 3 K
Liquid Nitrogen @ 77K

3. Oct 3, 2005

### z-component

The unit is called Kelvin, and absolute zero is 0 Kelvin or -273 degrees Celcius.

4. Oct 3, 2005

### killerinstinct

Absolute zero is characterised as 0 kelvins or 0 degrees Rankine, −273.15 °C, −459.67 °F.
i'm not a chemist, but i bash chemists for their incompetence.
I would suppose liquid nitrogen...

5. Oct 3, 2005

### Grogs

It's -273.15 degrees celcius. Celcius to kelvin is an easy conversion since 1 degree celcius is the same as one kelvin, so T(kelvin) = T(celcius) + 273.15 degrees.

Understand first that Helium and Nitrogen aren't superconductors. They're used to cool the superconductors. Once you drop the temperature of the superconductive substance low enough, the internal resistance drops to near zero (it becomes a superconductor.) As far as what's going on with the superconductive material, they're both going to behave the same way once they reach the critical temperature.

The main difference is going to be cost. With it's higher boiling point, liquid nitrogen is *much* cheaper than liquid helium. The superconductor with the higher critical temperature will be more attractive from that perspective.

6. Oct 3, 2005

### gapgirl1010

OKay, I get that thanks!

7. Oct 3, 2005

### Viper2838

Well, first look at the boiling point of each liquid. Nitrogen condenses at 77 K while Helium condenses at 4.22 K.
It becomes increasingly expensive to cool something down. The closer to absolute zero (0K) something is cooled, the more it will cost.
Now, I believe that most superconductors must be chilled down below roughly 60 K. Most of the research today has been focusing on creating superconductors that can be cooled by Nitrogen.
Given this information and the information you already stated, how do you think the direction of the field will be affected?
~Steve

Last edited: Oct 3, 2005
8. Oct 3, 2005

### Integral

Staff Emeritus
I have merged the 2 He/Hy threads, one is enough.