Question

Problem 24.53 - MC Bats are capable of navigating using the earth's field-a plus for an animal that may fly great distances from its roost at night. If, while sleeping during the day, bats are exposed to a field of a similar magnitude but different direction than the earth's field, they are more likely to lose their way during their next lengthy night flight. Suppose you are a researcher doing such an experiment in a location where the earth's field is 50 uT at a 60° angle below horizontal. You make Figure < 1 of 2 > SOUTH NORTH 60°

Answer 1

The arrangement that I made is of a solenoid of n turns carrying current I and radius r.

So, magnetic field of such a solenoid is

Mon/ B = 2r

$\mu_0$ is the permeability due to free space

Given that,

Β = 50 μT

n = 250

cm = 40 cm = 0.4 m 100

Putting the values,

50 x 10-6 = 6 47 x 10-7 x 250 x I 2 x 0.4

or, I = 0.127 A