Weird Science: Chip Bag Sparks - Hawaii News Now - KGMB and KHNL

Weird Science: Chip Bag Sparks

HONOLULU (HawaiiNewsNow)-Dr. V is back for a simple experiment that needs your parents supervision! Check out the video with an adult before trying this experiment on your own. 

Chip Bag Sparks

Things you will need:
•    Empty small chip bags
•    Microwave oven

The Experiment:
Please do this and all other experiments with the supervision of an adult. Place your empty chip bag in the microwave. Heat it on high for NO LONGER than four seconds. If you heat it any longer, you could damage the microwave oven. What happens to your chip bag? After you heat it, wait till it cools off and take it out of the microwave oven. What does your chip bag feel like? What does it look like?

How does it work?
You should have seen some fireworks in your microwave oven from your chip bag. Afterwards, your chip bag probably felt stiffer and was a lot smaller. Did you notice the inside of the chip bag is shiny silver? The bag is made of thin aluminum foil sandwiched between plastic. The aluminum helps to keep the bag airtight. Microwaves are a type of electromagnetic wave; when they hit the aluminum, they make electric currents flow back and forth in the aluminum foil. These electric currents heat up the foil in the same way a light bulb or toaster heats up. The plastic part of the bag is made of long polymer molecules that are stretched out until they are almost straight. When you heat up the bag, you give the molecules energy and they start to vibrate and wiggle. The molecules will tend to crinkle up and get less straight, becoming thicker and stiffer. This is why your chip bag feels different and looks smaller out of the microwave. As the aluminum is heated, the current tries to flow through it. If the aluminum were a smooth piece, the current could flow very easily and unrestricted.  But your chip bag is not smooth, it is pretty crinkly, and gets more so as it heats up. When the large current flowing through the bag reaches a crack in the foil, it will want to keep flowing, and if there is no foil, the next place it will flow through is the air. Because air is not a good conductor (electricity does not flow through air very well), it involves ripping electrons off their atoms, making it very hot and producing a lot of energy. This energy gets released as light, making a spark. Because the hot air heats up so quickly, it expands explosively, making a snapping sound.

 

 

 

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