Effect of magnetic field-Meissner effect

Meissner and Ochsenfeld in 1933 found that if a superconductor iscooled in a magnetic field below the transition temperature, themagnetic flux lines are pushed out of the body of the superconductor.This phenomenon is called Meissner effect which establishes that asuperconductor is a perfect diamagnet.Inside the specimen, B=0
But B = H + 4MH + 4M = 0Or H = -4MMagnetic susceptibility  = -1/4