Question

The total intensity of the earth's magnetic field at equator is $5$ units. What is its value at the poles?

• A. $5$
• B. $4$
• C. $3$
• D. $2$

Answer 1

Answer: (A)

$5$

Equator, $\theta =0^o,B_H=B_e\cos \theta =5\cos 0^o=5$
At poles, $\theta ={90}^o,V=B_e\sin \theta =5\sin {90}^o=5$
Thus, the total intensity of earth's magnetic field at poles is also $5$ units, but in the vertical direction. At equator, value is the same, but the direction is horizontal.