Electric current certain materials when cooled below a characteristic critical temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of "perfect conductivity" in classical physics. In a semiconductor it is sometimes useful to think of the current as due to the flow
Pieter Zeeman the phenomenon and submitted it to Nature, where it was published. The editor praised ""the careful observations of Professor Zeeman from his observatory in Zonnemaire"". After finishing high school in 1883, Zeeman went to Delft for supplementary education in classical languages, then a requirement for admission to University. He stayed at the home of Dr J.W. Lely, co-principal of the gymnasium and brother of Cornelis Lely, who was responsible for the concept and realization of the Zuiderzee Works. While in Delft, he first met Heike Kamerlingh Onnes, who was to become his thesis adviser. After Zeeman passed the qualification exams