Introduction to gpsurya blog

$Dear$ $Friends,$ In this blog you will find around 320 solved Geophysics GATE and CSIR-NET and other competitive exams solutions with a better explanation. Please follow and share if you like it. $Thanks,$ $gpsurya$ and $group$

CSIR-NET 2018 Dec-110

1 comment

 Q) A strongly magnetic spherical specimen when exposed to a magnetic field of 18.8 Oe exhibited an induced magnetism of 2.1 gauss. The susceptibility of the specimen (in cgs units) is   


(Special thanks to Rohit Jha & Chandrasekhar, AKNU)


Solution:

In general, induced magnetism(M) is defined as the product of magnetic susceptibility(K) and the external magnetic field(H).


              $M=K\times H$----------------------------(1)


 Given that M = 2.1 gauss

                    H = 18.8 Oe.


Here we cannot directly calculate the magnetic susceptibility because there is a difference in the induced magnetic field and the external magnetic field though they have the same sign, which gives the concept of Demagnetization.

               When there is Demagnetization, we use the apparent magnetic susceptibility, Ka.

Then eq(1) becomes $M=K_{a}\times H$


$K_{a}=\frac{M}{H}$


$K_{a}=\frac{2.1}{18.8}=0.111$-------------------------(2)


Where,


$K_{a}=\frac{K}{1+NK}$-------------------------------(3)

 

For the spherical objects $N=\frac{4\pi}{3}$


Substitute in eq(3) we get


$K_{a}=\frac{K}{1+(\frac{4\pi}{3})K}$

 

$\frac{K}{1+(\frac{4\pi}{3})K}=0.111$

 

$K=0.111(1+(\frac{4\pi}{3})K)$

 

$K=0.111+0.4647\times K$

 

$K(1-0.4647)=0.111$

 

$K(0.5353)=0.111$

 

$K=\frac{0.111}{0.5353}$

 

$k=0.207\sim 0.21$




Reference:  Applied Geophysics by W.M. Telford , L.P. Geldart and R.E.Sheriff.

Related Posts

1 comment

  1. Thank you for the helpful blog, "CSIR-NET 2018 Dec-110." I want you to know that your information is invaluable for aspiring candidates. Keep sharing valuable updates!
    Chandu Biology Classes

    ReplyDelete

Post a Comment

Subscribe Our Newsletter