Square meter

It might be noted that only for particles smaller than about 1 /ig or of surface area greater than a few square meters per gram does the surface energy become significant. Only for very small particles does the edge energy become important, at least with the assumption of perfect cubes. 

Dye adsorption from solution may be used to estimate the surface area of a powdered solid. Suppose that if 3.0 g of a bone charcoal is equilibrated with 100 ml of initially 10 Af methylene blue, the final dye concentration is 0.3 x 10 Af, while if 6.0 g of bone charcoal had been used, the final concentration would have been 0.1 x Qr M. Assuming that the dye adsorption obeys the Langmuir equation, calculate the specific surface area of the bone charcoal in square meters per gram. Assume that the molecular area of methylene blue is 197 A. ... 

Plot the data according to the BET equation and calculate Vm and c, and the specific surface area in square meters per gram. 

Gram per square meter ounce per square foot 0.327 706... 

Lumen per square meter lumen per square foot 0.092 903 0... 

Polarizability volume (47reo cm ) coulomb squared-(meter squared per joule) 1.112 65 X 10- ... 

Pound per square foot kilogram per square meter 4.882 43... 

Stokes (kinematic viscosity) square meter per second 10- ... 

Watt per square inch watt per square meter 1550.003... 

If the amount of light is measured over an area of receiving surface, the energy falling on the surface is measured in lumens per unit area ( lux" or phof). Thus, the number of lux = Iumens/m2 and this measures the power received per square meter of surface (energy per second/per unit area) and phot = Iumens/cm2 and measures the light power received per square centimeter of surface. 

The small cross-sectional area covered by a laser light beam coupled with the energy density in the beam leads to power levels reaching from milliwatts to many hundreds of kilowatts per square meter. 

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