13.2 Magnetic Pressure Now we put this sheet into a given uniform magnetic field B′=p0O Thus on one side of the sheet the magnetic fields cancel, 10c/2-10/2=0 and on the other side they add up 40/2+140/2=10=2B The force on the sheet per unit area( pressure)is =axB′=a(0/2)=a210/2=(2B220