^Comparative study of Dia, para & ferro

^Comparative study of Dia, para & ferro

Property	Diamagnetic	Paramagnetic	Ferromagnetic
Physical state	Solid, liquid or gas	Solid, liquid or gas	Crystalline solids only
Atomic dipole moments	Zero permanent dipole moment	Non – zero permanent dipole moments but oriented randomly	Non – zero permanent dipole moments but organised in domains
Effect of external mag. field	Feebly repelled	Feebly attracted	Strongly attracted
A freely suspended rod in a uniform magnetic field	A diamagnetic rod aligns itself normal to field	A paramagnetic rod aligns itself along field	A ferromag. rod quickly aligns itself along field
In a non uniform magnetic field	Tend to move slowly from stronger to weaker field.	Tend to move slowly from weaker to stronger field	Tend to move quickly from weaker to stronger.
Intensity of magnetization	Small – ve	Small +ve	Large +ve
Relative permeability (μ_r)	0 ≤ μ_r < 1 (slightly)	μ_r > 1 (slightly)	> 1 Quite large ( ≈ 10¹²)
Permeability	μ < μ₀	μ > μ₀	μ >>μ₀
Mag. susceptibility	Small – ve (≈ 1)	Small + ve (≈ 1)	Large + ve ( ≈ 10¹²)
B in a medium is	More than in diamagnetic	Less than in a paramagnetic	Much lesser in a ferromagnetic
Dependence of χ_mon H	Independent	Independent	Independent
Dependence of χ_mon H	χ ∝ T⁰	(Curie law)	(Curie weiss)
Can be explained by	Orbital motion of electrons	Spin motion of e^– s (90%)	Domain Theory
Transition	No	Para increases (on cooling)	Ferro® para (on heating)
Effect of temperature	No effect (Except Bi at low T)	Decreases	Decreases (T=T_C, F → P)
Examples	People, frogs, bismuth, copper, gold, zinc, silver, Diamond, graphite, mercury, lead, water, hydrogen, nitrogen (at NTP),NaCl, CO₂, benzene & all inert gases.	Transition elements, rare earth elements and actinide elements, oxygen gas, air, aluminum, tungsten, titanium, cerium.	Iron, cobalt, nickel, gadolinium, dysprosium, Fe₂ O₃, alnico and alloys containing these elements.