## What is the formula for cross-sectional area?

Cross-sectional area is determined by squaring the radius and then multiplying by 3.14. For example, if a tree is measured as 10” DBH, the radius is 5”. Multiplying 5 by 5 equals 25, which when multiplied by 3.14 equals 78.5. Thus, the cross-sectional area of a 10” DBH tree is 78.5.

### How do you find the surface area of a Langmuir?

I tried BET and Langmuir model for this purpose. But I am stuck. The formula for Total surface area is: St = (W N A)/M where N is Avogadro number, M is molecular weight of adsorbate, W is weight of monolayer and A is Adsorbate cross sectional area.

#### How do you calculate cross-sectional resistivity?

Resistivity, commonly symbolized by the Greek letter rho, ρ, is quantitatively equal to the resistance R of a specimen such as a wire, multiplied by its cross-sectional area A, and divided by its length l; ρ = RA/l. The unit of resistance is the ohm.

**What is Langmuir?**

The langmuir (symbol: L) is a unit of exposure (or dosage) to a surface (e.g. of a crystal) and is used in ultra-high vacuum (UHV) surface physics to study the adsorption of gases. It is a practical unit, and is not dimensionally homogeneous, and so is used only in this field.

**What is Langmuir constant?**

The Langmuir constant (K) indicates the extent of interaction between adsorbate and the surface. If the value of K is relatively larger it indicates that there is a strong interaction between adsorbate and adsorbent while smaller value implies a weak interaction.

## What is resistivity formula?

### How do we calculate resistivity?

The resistance is calculated as the ratio of voltage (V) to the current (I) applied on a material and the resistivity is the ratio of the electric field (E) to the current density (J). The resistance is measured in terms of ohms whereas resistivity is measured in terms of ohms metre.

#### What is B in Langmuir adsorption?

The Langmuir adsorption isotherm can be written:θ=bp/(1+bp), where θ is the fraction of the surface covered by the adsorbate, p is the pressure of the gas, and b is a constant called the adsorption coefficient, which is the equilibrium constant for the process of adsorption.