A student wraps copper wire around an iron nail. Then she connects the ends of the wire to a battery, making an electromagnet. She notices that if she wraps more coils of wire around the bolt, then her electromagnet can pick up more paper clips. What conclusion can she draw? (1 point)
More coils of wire increases the length of the nail
More coils of wire increases the strength of the electromagnet
More coils of wire increases the mass of the battery
More coils of wire increases the density of the copper wire