The area vector of a square loop of 5 turns of a conductor each with side length of 0.2 m carrying a current of 2 A is antiparallel to a uniform magnetic field of 50.0 T in which it lies. Question 5. The magnitude and direction of the total magnetic moment is ……to the area vector.

it is called kinetic energy

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.

the doppler effect is used by weather forecasters to measure 

moving clouds