The inter atomic distances of H2 should be much larger than mono atomic helium I think.
But I learned something new today. I was also mis-informed. I guess helium is used for safety.
Thanks.
But I learned something new today. I was also mis-informed. I guess helium is used for safety.
Thanks.
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According to Wiki, the Hydrogen molecule has a kinetic diameter of 289 pm (picometre), while Helium has “just” 260 pm.
So the Hydrogen molecule is 11% bigger than Helium.
So the Hydrogen molecule is 11% bigger than Helium.
I've been looking more things up! 😉
Specific acoustic resistance is useful in discussing waves in confined gases such as in tubes and horns.
The specific acoustic impedance of a gas is the product of its density and the speed of sound in the gas (z = ρ×c)
It's a measure of the opposition to the acoustic flow resulting from an applied acoustic pressure, and is analogous to electrical impedance which measures the opposition to the electric current resulting from an applied voltage.
Air (at 20 degrees C) has a z of 0.0004 Pa.s/m, while helium has a z of 0.0016 Pa.s/m.
Therefore helium has 4 times the z of air, which means that sound propogates 4 times more easily through air than through helium.
I hope that's useful! 🤔
Harmonic distortion? (Due to the asymmetrical mass and compressibility.)
That’s an interesting observation. I guess they’d be evens due to the asymmetry. Some might like that!
By the way, a completely air- or helium-tight closed box would lead to the cone being pressed inward or outward depending on barometric pressure variations.
That's why Dave mentioned putting the 'special' gas in a plastic bag, leaving air in the remainder of the loudspeaker enclosure.
Of course, the plastic bag would have to be non-porous.
Such an arrangement would allow air to leak in and out of the enclosure to ensure barometric equalisation.
Of course, the plastic bag would have to be non-porous.
Such an arrangement would allow air to leak in and out of the enclosure to ensure barometric equalisation.
It was very unscientific of me to state earlier that a hydrogen molecule was "smaller" than helium without stating in what respect it was smaller.
Rate of diffusion depends on the mass rather than diameter, so I should have said "smaller mass" from the outset.
I remember one of my old physics textbooks stating that comparing the diameter of the pores in the walls of a rubber balloon to the diameter of a gas molecule was like a comparing the entrance of a road tunnel to a bee!
The temperature of a gas is a measure of the average kinetic energy (KE) of its molecules. As we all know, KE = 1/2mv^2. In order to have the same average KE as monoatomic helium, the less massive hydrogen molecules at the same temperature must be moving faster on average. Their greater speed means a greater number of hydrogen molecules will encounter and escape through the pores in the walls of a balloon in a given time. In short, the rate of diffusion has to do with the speed of movement and not the diameter of the gaseous escapee.
Rate of diffusion depends on the mass rather than diameter, so I should have said "smaller mass" from the outset.
I remember one of my old physics textbooks stating that comparing the diameter of the pores in the walls of a rubber balloon to the diameter of a gas molecule was like a comparing the entrance of a road tunnel to a bee!
The temperature of a gas is a measure of the average kinetic energy (KE) of its molecules. As we all know, KE = 1/2mv^2. In order to have the same average KE as monoatomic helium, the less massive hydrogen molecules at the same temperature must be moving faster on average. Their greater speed means a greater number of hydrogen molecules will encounter and escape through the pores in the walls of a balloon in a given time. In short, the rate of diffusion has to do with the speed of movement and not the diameter of the gaseous escapee.
Assuming you solved the leaking issue, the less-dense helium or other gas less dense than air would cause a phase difference between the front and rear of the drivers. My guess is that it would harm sound more than improve it, not only because the potential for introducing unwanted harmonics but also because the drivers will experience less resistance from the less dense gas, on just one side, which would undoubtedly affect the mechanical properties of the drivers.
I'm reminded of the following videos which describe how helium can be used as an excellent sound suppressant:
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Helium is much smaller than H2 as its monoatomic. He radius is 0.031nm (0.3 Angstrom), H2 bond-length alone is more than double that...
Smallest by far is the hydrogen ion, which a bare proton. Protons diffuse readily through many materials. This is a bit misleading though as an ion always binds to other atoms and molecules, impeding its movement, whereas neutral helium only sees Van-der-Waals forces. Acids acting on metal surfaces can inject protons into the metal, which then diffuse to the other side and recombine to make H2 gas appear there!
Reading through, I was going to mention that there could be a bladder within the chamber. You beat me to it.
The above is true (see post #23).
However, if we're talking straightforward gaseous diffusion, the difference in diameters is irrelevant.
Diatomic hydrogen diffuses faster than monoatomic helium because of its smaller molar mass.
The speed of sound in a gas is related to the average speed of the particles in the gas,
The average speed is inversely proportional to the square root of the mass of each identical gas particle
Hence, the smaller the particle mass, the greater the average speed and the greater the speed of sound in the gas (at a given temperature).
The average speed is inversely proportional to the square root of the mass of each identical gas particle
Hence, the smaller the particle mass, the greater the average speed and the greater the speed of sound in the gas (at a given temperature).