How to Dim a Super Bright Book Light

Have you ever been reading with a book light at night and found it to be too bright? Here's a simple way to dim your book light without permanently changing it. This method reduces the amount of voltage supplied to the light, thus reducing the brightness. This will work with book lights that are powered by two button cell batteries. 

The aluminum foil is acting like a spacer. It conducts the electricity, but doesn't add any additional power. 

Please note that only one of the original batteries remains in the book light.