Apart from its use as a reactant, H
2 has wide applications in physics and engineering. It is used as a shielding gas in welding methods such as atomic hydrogen welding. H2 is used as the rotor coolant in electrical generators at power stations, because it has the highest thermal conductivity of any gas. Liquid H2 is used in cryogenic research, including superconductivity studies. Because H
2 is lighter than air, having a little more than 1⁄14 of the density of air, it was once widely used as a lifting gas in balloons and airships. COUNT 4
QSN1 Where else is H2 applied? ANS1 in physics and engineering QSN2 How is H2 used in electrical generators at power stations? ANS2 as the rotor coolant QSN3 Why is it used as the rotor coolant? ANS3 it has the highest thermal conductivity of any gas QSN4 What research uses liquid H2? ANS4 cryogenic