Which of the following does NOT increase the magnetic field strength of an electromagnet?
Using a stronger current
Increasing the temperature
Using a stronger magnetic material
Adding more coils
Increasing the temperature
What evidence supports the existence of fields between objects exerting forces on each other?
The objects need to be in motion.
The objects need to be in direct contact.
The objects need to be the same material.
The objects do not need to be in contact.