From building aircraft to keeping food safe in the kitchen, aluminum, a highly malleable, lowdensity metal, has become an essential part of modern life. Aluminum foil is probably one of the thinnest but solid materials available in a household. Measuring its thickness is an instructive exercise to understand different measuring instruments, methods and properties. Because it is so thin, the thickness of aluminum foil can’t be measured directly using household measuring tools like a ruler or a measuring tape. However, there are indirect ways to measure its thickness, one of which relies on its most useful characteristic  density.
Things You'll Need
 Balance (accurate to milligrams)
 Metric ruler
 Calculator
 Micrometer (optional)

Weigh a single sheet of aluminum foil using a precise balance that can measure in centimeters to find the thickness of aluminum foil indirectly. Divide it by 1,000 to get its mass in grams.

Measure the surface area of the aluminum foil in millimeters using a ruler. Surface area is calculated by multiplying the length by the width. For example, surface area of a foil measuring 5.0 cm by 5.0 cm equals 25.0 cm^2.

Use the formula for density to determine the thickness of aluminum foil. The standard equation is d = m / v, where density is mass divided by volume. Here, however, you substituting area thickness for volume, getting the equation d = m / (a t). Rearrange the equation algebraically to solve for thickness, giving the new equation, t = m / (a d). The standard density of aluminum is 2.702 grams per cubic centimeter. Continuing the example, an aluminum foil of mass 0.01 grams and area of 25 cm^2 has a thickness of 0.01/(25.02.702), which equals 0.000148 cm.
Tips & Warnings
 You can measure the thickness of aluminum foil directly with a micrometer.
References
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