A cylindrical superconductor of radius 200 cm with an axial hole in the center of radius 100 cm is located in a  parallel magnetic field of 2T at 300°K. It has a penetration depth of 2000 °A

a) What amount of flux is stored in the superconducting material and in the hole if the sample is cooled to 40°K, well below Tc = 90°K

b) If the applied reduced to 0.5 T, how will these stored fluxes change?

c) What is the value of current density on the outside surface and on the inside surface for these two cases?