A solid cylindrical rod made of a metallic alloy is placed inside the uniform…
PHYSICS · Multi-part · CBSE · Physics · Magnetism and Matter · Magnetism and Matter
Problem
A solid cylindrical rod made of a metallic alloy is placed inside the uniform magnetic field produced by a long solenoid. At room temperature (25 °C) the rod is strongly attracted to the solenoid core, and after the solenoid current is switched off the rod itself can pick up small iron filings. The same rod is then heated uniformly to 800 °C and immediately placed inside the energized solenoid again. This time the rod shows no noticeable attraction, and when the current is turned off it cannot pick up filings.
(The Curie temperature of pure iron is 770 °C.)
(a) Identify the type of magnetic behavior the alloy exhibits at 25 °C and at 800 °C. Justify each identification with reference to the observations.
(b) Explain qualitatively what happens to the arrangement of magnetic domains in the material as its temperature rises through the Curie temperature.
(c) Suppose the rod is slowly cooled back to room temperature while remaining inside the energized solenoid. Describe its final magnetic state once the solenoid current is turned off, and explain your reasoning.