Magnetism Question 252
Question: The earth’s magnetic field lines resemble that of a dipole at centre of the earth. If the magnetic moment of this dipole is close to $ 8\times 10^{22}Am^{2} $ , the value of earth’s magnetic field near the equator is close to (radius of the earth $ =6.4\times 10^{6}m $ )
Options:
A) 0.6 Gauss
B) 1.2 Gauss
C) 1.8 Gauss
D) 0.32 Gauss
Show Answer
Answer:
Correct Answer: A
Solution:
[a] Given $ M=8\times 10^{22},Am^{2} $
$ d=R _{e}=6.4\times 10^{6}m $ Earth’s magnetic field, $ B=\frac{{\mu _{0}}}{4\pi }.\frac{2M}{d^{3}} $
$ =\frac{4\pi \times {{10}^{-7}}}{4\pi }\times \frac{2\times 8\times 10^{22}}{{{(6.4\times 10^{6})}^{3}}} $
$ \cong ,0.6,Gauss $
BETA
