Question

At a certain location in Africa, a compass points 12° west of the geographic north. The north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points 60° above the horizontal. The horizontal component of the earth’s field is measured to be 0.16 G. Specify the direction and magnitude of the earth’s field at the location.

Answer 1

Answer:

Angle of declination, θ=12  

∘

 

Angle of dip, δ=60  

∘

 

Horizontal component of earths magnetic field, B  

H

​  

 = 0.16 G

We can write,

B  

H

​  

=Bcosδ

where, B is Earths magnetic field at the given location  

B=  

cosδ

B  

H

​  

 

​  

 

B=  

cos60  

∘

 

0.16

​  

 

B=0.32G=0.32×10  

−4

T

Earths magnetic field lies in the vertical plane, 12  

∘

 West of the geographic meridian, making an angle of 60  

∘

 (upward) with the horizontal direction. Its magnitude is 0.32×10  

−4 T.