Chapter 36, Problem 28A

A friend tells you that a refrigerator door, beneath a layer of white-painted plastic, is made of aluminum. How could you check to see if this is true (without any scraping)?

To determine

A way to determine that refrigerator door is made of aluminum without any scraping.

Explanation of Solution

Introduction:  Magnetism is a type of force exerted by a magnet. Magnets can attract or repel each other. Some pure metals do not exhibit the magnetism like aluminum, copper, gold, etc. but the ferromagnetic metals like iron, nickel, and cobalt exhibit the magnetism at room temperature. 

Aluminum is a material that does not exhibit the property of magnetism. Naturally, aluminum is a pure metal and it does not have any ferrous (iron)content. 

So, to verify that a refrigerator door is made of aluminum beneath a layer of white-painted plastic, perform a test with the magnet. If a magnet sticks to the white painted plastic door, it’s not the aluminum because the aluminum does not have a magnetic property. 

Conclusion:  By performing a test with a magnet on the white-plastic refrigerator door, it can be concluded whether it is aluminum or not.