Reference Module in Materials Science and Materials Engineering MATS 01908

The cryogenic current comparator is used to maintain national representations of the ohm based on the quantized Hall resistance standard. The measurement technique utilizes the Meissner effect to establish accurate resistance ratios with specialized cryogenic bridge circuits. In these bridges identical voltages appear across the resistance elements to be compared, and the unknown resistance can be calculated from the ampere-turns balance maintained by a superconducting quantum interference device.