KEAM 2021 Physics and Chemistry Solved Paper

At the magnetic equator, angle of dip(θ) is 0∘.
As, H=Be‌cos‌θ
where, Be is the net magnetic field and H is the horizontal component of Be.
⇒‌‌H‌‌=Be‌cos‌0∘=Be
V‌‌=Be‌sin‌0∘=0
Total intensity of magnetic field,
B=√H2+V2=Be...(i)
However, θ at poles is 90∘.
⇒‌‌H‌‌=Be‌cos‌90∘=0
V‌‌=Be‌sin‌90∘=Be
⇒ Total intensity of magnetic field,
B=√H2+V2=Be
Given, Be=7 ....(ii)
From Eqs. (i) and (ii), we get
Total intensity of earth's magnetic field at equator =7 units