For a conductor in electrostatic equilibrium, which of the following properties are true? a) Any excess charge is uniformly spread throughout the volume of the conductor.
b) The electric field inside is zero.
c) The entire conductor is at the same potential.

b) The electric field inside is zero.

Explanation:

This is simply because the charges in the field will be in motion, thus this charges kind of spread around to make the conductor field zero.

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.