Question

If the magnitude of the earth's magnetic field at the equator is $3.3\times {10}^{-5}T$, then find the magnitude of the field at the poles :

• A. $3.3\times {10}^{-5}T$
• B. $6.6\times {10}^{-5}T$
• C. $8.4\times {10}^{-5}T$
• D. none of these

Answer 1

Answer: (B)

$6.6\times {10}^{-5}T$

Given that earth's magnetic field at equator is $B=3.3\times {10}^{-5}$
$B=B\sqrt{1+3{\sin }^2\lambda }$
Here angle between equator and pole is $\lambda =\frac{\pi }{2}$
$B=3.3\times {10}^{-5}\times 2$
$B=6.6\times {10}^{-5}T$