The transition temperature for Pb is 7.2K, however, at 5K it loses the superconducting property subjected to a magnetic field of 3.3 x 10^4 A/m.

The transition temperature for Pb is 7.2K, however, at 5K it loses the superconducting property subjected to a magnetic field of 3.3 x 10^4 A/m. Find the maximum value of H which allow the metal to retain its superconductivity at 0 Kelvin.