If a major asteroid collision in the asteroid belt occurs, on average, 1 time in 100,000 years, then how many major collisions have occurred over the approximately 4 billion year history of the solar system?

a) about 40,000
b) about 4 billion (correct answer)
c) about 4 million
d) about 4,000

c) up is the direction the magnetic force is acting on the charge.

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.