Three compasses are shown next to a wire carrying a positive current (towards the viewer). The strength of the total magnetic field at the location of the left compass is 0.30 G. The strength of the total magnetic field at the location of the right compass is 0.40 G. Which of the following best describes the strength of the total magnetic field at the location of the middle compass?

A. Between 0.00G and 0.30 G
B. Exactly 0.30 G
C. Between 0.30 G and 0.40 G
D. Greater than 0.40 G

a.metals can become magnetic if they have many spinning electrons that create magnetic fields.d.only some metals are attracted by magnets; these metals are called ferromagnetic.

d.wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.

does anyone know or what?

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

i think its c if i'm wrong