Key relationship
M=χH; B=µ₀(1+χ)H.
Physics · Class 12
Dia, para and ferromagnetism
Diamagnetic susceptibility is weak and negative; paramagnetic susceptibility is weak and positive. Ferromagnetism can be much stronger and nonlinear; this lesson uses an explicitly simplified temperature-dependent linear response.
Open the interactive experiment →Dia, para and ferromagnetism
எதிர்காந்தத்தில் χ எதிர்மறை. துணைக்காந்தத்தில் χ நேர்மறை. இரும்புக் காந்தத்தின் மறுமொழி மிகவும் வலியது.
Key notes, relationships and model limits
Remember
Diamagnetic susceptibility is weak and negative; paramagnetic susceptibility is weak and positive. Ferromagnetism can be much stronger and nonlinear; this lesson uses an explicitly simplified temperature-dependent linear response.
Common trap
Diamagnetic susceptibility is negative; paramagnetic susceptibility is positive. A linear susceptibility is a simplified material model.
Model limits
Illustrative linear response, χdia=−10⁻⁵, χpara=0.3/T; ferromagnetic response is bounded and excludes hysteresis, domains and saturation.
What you will learn
Use the controls and plotted relation to explain dia, para and ferromagnetism.
Try the experiment
Try both scenarios, change one control, and predict the result before checking the graph and readouts.
Think of it this way
Change one input while keeping the others fixed, as you would in a controlled experiment.
Worked example
For χ=−10⁻⁵ and H=100 A/m, M=−0.001 A/m, opposing the applied field.
Why this matters
The model connects dia, para and ferromagnetism with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
A diamagnetic material has susceptibility?
- Small and positive.
- Small and negative.
- Large and always positive.
Read the explanation
Small and negative.
Course connection: Class XII Chapter 5. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.