At the equator, the earth’s field is essentially horizontal; near the north pole, it is nearly vertical. In between, the

[answerhappygod]

At the equator, the earth’s field is essentially horizontal;
near the north pole, it is nearly vertical. In between, the angle
varies. As you move farther north, the dip angle, the angle of the
earth’s field below horizontal, steadily increases. Green turtles
seem to use this dip angle to determine their latitude. Suppose you
are a researcher wanting to test this idea. You have gathered green
turtle hatchlings from a beach where the magnetic field strength is
50 μTμT and the dip angle is 56∘∘. You then put the
turtles in a 1.4 mm diameter circular tank and monitor
the direction in which they swim as you vary the magnetic field in
the tank. You change the field by passing a current through a
250-turn horizontal coil wrapped around the tank. This creates a
field that adds to that of the earth.
What current should you pass through the coil, to produce a net
field in the center of the tank that has a dip angle of
62∘∘ ?