A student made an electromagnet using an iron bolt, copper wire coiled three times around the bolt, and a battery. How can he increase the strength of his magnet?
Add batteries to increase the voltage, and decrease the space between the coils of wire
Add batteries to decrease the voltage, and decrease the space between the coils of wire
Add batteries to decrease the voltage, and increase the space between the coils of wire
Add batteries to increase the voltage, and increase the space between the coils of wire