Physics Magnetism and Matter

Diamagnetic materials create an induced magnetic field in a direction opposite to an externally applied magnetic field, and hence are repelled by the applied magnetic field.

In JEE Main exam, it is a significant chapter. There can be 6 to 8 questions from this chapter, a weightage of nearly 6.6%.

The exact weightage varies from year to year. This chapter comes under a broader category which can be "Magnetism" or "Modern Physics". In NEET exam, the chapter's weightage is low to moderate and there can be 6-7% of questions from this chapter.

The chapter is one of the small and easy chapter of class 12 Physics. It includes - properties of magnetic materials, magnetic dipoles, and Earth's magnetic field.

When the electric charges moves, it creates attraction or repulsion. It creates magnetic forces and fields and called magnetism. The term "magnetism and matter" talks about the way magnetic forces and matter interact.

For diamagnetic ; $\chi <0andl=\chi H$

$M={\chi }_{m}H$ and ${}_{}\frac{}{}$ ${\chi }_m=\frac{C}{T}($ Curie law $$ $)$ ,

$$ $M=\frac{CH}{T}$  or $\frac{M_1}{M_2}=\frac{C{H}_1/T_1}{C{H}_2/T_2}=\left(\frac{H_1}{H_2}\right)\left(\frac{T_2}{T_1}\right)$ $\frac{{}_{}}{{}_{}}\frac{{}_{}{}_{}}{{}_{}{}_{}}\left(\frac{{}_{}}{{}_{}}\right)\left(\frac{{}_{}}{{}_{}}\right)$

$M_2=M_1\left(\frac{H_2}{H_1}\right)\left(\frac{T_1}{T_2}\right)=12(\mathrm{A}/\mathrm{m})\left[\frac{0.2T}{0.6T}\right]\left[\frac{4\mathrm{K}}{16\mathrm{K}}\right]$

$=1\mathrm{A}/\mathrm{m}$

Kindly consider the following Image 

The Earth's magnetic field makes a magnetic inclination (dip) or angle between Earth's overall magnetic field and the horizontal plane at a particular location. It shows how much the magnetic field is tilted from the horizontal.

tan I = B_V / B_H,

where, B_V is the vertical component and B_H is the horizontal component of the Earth's magnetic field.