We have seen that the heart produces a magnetic field, and that this can be used to diagnose problems with the heart. The magnetic field of the heart is a dipole field that is produced by a loop current in the outer layers of the heart. Suppose the field at the center of the heart is 90 pT (a pT is 10−12T ) and that the heart has a diameter of approximately 12 cm. What current circulates around the heart to produce this field?

Current circulating is 8.59×10^-6A

Explanation:

Magnetic field at the center of the loop is given by, B= μI/2R

I = 2RB/μ

given that B is 90x 10^-12 T

radius is 0.12 m /2 = 0.06m

we know that μ is 4π x 10^-7 T.A/m

Substituting the given values we get,

I= (((2(0.06m)(90x 10^-12 T))/(4π x 10^-7 T.A/m))

I is 8.59 x 10^-6 A

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia