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Statement A: A proton has spin and magnetic moment just like an electron. But its effect is neglected in magnetism of materia. Statement B: The order of magnitude of difference between the diamagnetic susceptibility of N_(2)(~5xx10^(-9))(STP) and Cu(~10^(-5)) is 1.6xx10^(-4) Statement C: Suppose we want to verfty the analogy between electrostatic and magnetostatic by an explicit experiment. Consider the motion of (i) electric dipole P in an electrostatic field E and (ii) magnetic dipole M in a magnetic field B . Set of conditons on E,B,p,M so that two motions are verified to be identical. (Assume identical initial contiditions) are (i) P=(M)/(C ) ,(ii) PE=MB |
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Answer» `A` correct `B` correct `C` correct `M=(EH)/(4pim)` or `M prop(1)/(m)` `(therefore (eH)/(4pi)="constant")` `therefore (M_(p))/(M_(e))=(m_(e))/(m_(p))` `therefore =(M_(e))/(1837M_(e))` `(thereforeM_(p)=1837 m_(e))` `rArr(M_(p))/(M_(e))=(1)/(1837)ltlt1` `rArr (M_(p)ltltM_(e))` Thus,effect of magnetic moment of proton is neglected as COMPARED to that of electron. B) We know that Density of nitrogen`rho_(N_(2))=(28g)/(22.4L)=(28g)/(22400c c)` Also, density of copper `rho_(Cu)=(8g)/(22.4L)=(8g)/(22400 c c)` Now, comparing both densities `(rho_(N_(2)))/(rho_(Cu))=(28)/(22400)xx(1)/(8)=1.6xx10^(-4)` Also given `(X_(N2))/(X_(cu))=(5xx10^(-9))/(10^(-5))=5xx10^(-4)` We known that, `X=("Magnetisation"(M))/("Magnetic int ensity (H)")` `=(M)/(HV)=(M)/(H("mass"//"density"))=(M_(p))/(HM)` `therefore X prop raho` Hence, `(X_(N_(2)))/(X_(Cu))=(rhoN_(2))/(rho_(cu))=1.6xx10^(-4)` Thus, the order of magnitude difference or MAJOR difference between the diamagnetic susceptibility of `N_(2)` and `Cu` is accounted for by the ratio of densities . C) Now, suppose that the angle between `M` and `B` is `theta` Torque on magnetic dipole moment `M` in magnetic field `B`. `tau'=MB sin theta` Two motions will be identical, if `pE sin theta=MB sin theta` `rArr pE=MB` But, `E=cB` `therefore` Putting this value in `Eq.(i), pcB=MB` `rArr p=(M)/(c)` |
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