An unmagnetized steel bar is placed inside a solenoid. As the current in the solenoid is slowly increased from zero to some large value, the magnetization of the bar: 0 increases proportionally with the current 0 increases with increasing current atflrst but later is much less affected by it 0 increases quadratically with the current 0 is unaffected by the current 0 remains zero for a while and then increases linearly with any further increase in current