The correct value of dip angle at a place is 45o. If the dip circle is rotated by 45o out of the meridian, then the tangent of the angle of apparent dip at the place is :
Let δ1
be the angle of dip when dip circle is in magnetic meridian
tanδ1=VH
The dip circle when makes an angle
θ , horizontal component of the earth's magnetic field is
Hcosθ
The angle of dip when dip circle makes an angle
with the magnetic meridian is,
tanδ1=VHcosθ
tanδ1=tanδcosθ
tanδ1=√2