In the intensity equation I = I0 e^(-μ x), what is the unit of μ (mu)?

In the intensity equation I = I0 e^(-μ x), what is the unit of μ (mu)?

• A. Inverse centimeters
• B. Inverse meters
• C. Centimeters
• D. Unitless

Answer: (A)

In the intensity equation, the exponent must be dimensionless, so the product μ x has no units. That forces μ to have units of 1/length. Since x is typically measured in centimeters in this formulation, μ carries the unit of per centimeter (inverse centimeters). If x were in meters, μ would be per meter instead. The value of μ depends on the material and the photon energy, but its unit is always reciprocal length.

In the intensity equation, the exponent must be dimensionless, so the product μ x has no units. That forces μ to have units of 1/length. Since x is typically measured in centimeters in this formulation, μ carries the unit of per centimeter (inverse centimeters). If x were in meters, μ would be per meter instead. The value of μ depends on the material and the photon energy, but its unit is always reciprocal length.