Pamela produced an electromagnet by wrapping a copper wire around an iron nail. When she connected the wire ends to a battery, she was able to lift 4 paper clips with her electromagnet. She decided that she wanted to modify the electromagnet so that it would lift 7 paper clips. She modified the electromagnet by removing the iron nail and replacing it with an aluminum nail. However, when she modified the electromagnet, it would not lift any paper clips.

Explain why Pamela's modification caused the electromagnet to lose its magnetic properties.​