lambda point
Quick Summary
The lambda point is a specific temperature, approximately 2.19 Kelvin, at which liquid helium transitions from a state called helium I to a state known as helium II. This transition is also referred to as the lambda transition.12
Helium I is the normal liquid helium that boils at 4.2 Kelvin under standard atmospheric pressure. It exists between the critical point of 5.2 Kelvin and the lambda point of 2.19 Kelvin. Below the lambda point, helium exhibits superfluidity, characterized by frictionless flow and other unusual behaviors arising from quantum mechanical effects.32
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