The angle of dip is the angle between earth's horizontal magnetic field and magnetic field produce by coil .

But I could not understand when current is reversed the angle of dip changes but magnitude of magnetic field is same .

2 votes

The angle of dip is the angle between earth's horizontal magnetic field and magnetic field produce by coil .

But I could not understand when current is reversed the angle of dip changes but magnitude of magnetic field is same .

Let $B_v$ and $B_h$ be vertical and horizontal component of magnetic field. K be magnetic field by coil.

Then $B_v/(B_h +k) = tan(30°)$

And $B_v/(B_h-k) = tan(60°)$ .

Now what to do .

Then $B_v/(B_h +k) = tan(30°)$

And $B_v/(B_h-k) = tan(60°)$ .

Now what to do .

You are given $B_h$. The 2 unknowns are $B_v$ and $K$. Eliminate $B_v$ to find $K$. Then relate that to the current in the coil.

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edited Feb 21, 2017 by sammy gerbil