A permanent bar magnet is slowly heated to just below its Curie temperature and then…
PHYSICS · Single correct · CBSE · Physics · Magnetism and Matter · Magnetism and Matter
Problem
A permanent bar magnet is slowly heated to just below its Curie temperature and then allowed to cool in the absence of any external magnetic field. Which outcome is most likely, and why?
(a) Its magnetic strength increases because the expanded lattice allows domains to align more perfectly upon cooling.
(b) Its polarity reverses because the North–South orientation flips when the magnet is heated near the Curie point.
(c) Its magnetic strength decreases because thermal agitation randomizes many of the previously aligned domains.
(d) Its magnetic strength returns to essentially its original value after cooling, since the removal of thermal agitation lets the original domain alignment re-establish itself even without an external field.