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1 Bq = 1 s −1. A special name was introduced for the reciprocal second (s −1) to represent radioactivity to avoid potentially dangerous mistakes with prefixes.For example, 1 μs −1 would mean 10 6 disintegrations per second: (10 −6 s) −1 = 10 6 s −1, [4] whereas 1 μBq would mean 1 disintegration per 1 million seconds.
The rules of radioactive decay may be used to convert activity to an actual number of atoms. They state that 1 Ci of radioactive atoms would follow the expression N (atoms) × λ (s −1) = 1 Ci = 3.7 × 10 10 Bq, and so N = 3.7 × 10 10 Bq / λ, where λ is the decay constant in s −1. Here are some examples, ordered by half-life:
Conversion of units is the conversion of the unit of measurement in which a quantity is expressed, typically through a multiplicative conversion factor that changes the unit without changing the quantity. This is also often loosely taken to include replacement of a quantity with a corresponding quantity that describes the same physical property.
The mass of an object is a measure of the object’s inertial property, or the amount of matter it contains. The weight of an object is a measure of the force exerted on the object by gravity, or the force needed to support it. The pull of gravity on the earth gives an object a downward acceleration of about 9.8 m/s 2. In trade and commerce and ...
In water solutions containing relatively small quantities of dissolved solute (as in biology), such figures may be "percentivized" by multiplying by 100 a ratio of grams solute per mL solution. The result is given as "mass/volume percentage". Such a convention expresses mass concentration of 1 gram of solute in 100 mL of solution, as "1 m/v %".
The specific weight, also known as the unit weight (symbol γ, the Greek letter gamma), is a volume-specific quantity defined as the weight W divided by the volume V of a material: = / Equivalently, it may also be formulated as the product of density, ρ, and gravity acceleration, g: = Its unit of measurement in the International System of Units (SI) is newton per cubic metre (N/m 3), with ...
However, if the time includes year as the unit of measure, the dimension of the rate is 1/year. Of course, there is nothing special (apart from the usual convention) about using year as a unit of time: any other time unit can be used. Furthermore, if rate and time include their units of measure, the use of different units for each is not ...
The quantity "1 ppm" can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is common to assume that the density of water is 1.00 g/mL. Therefore, it is common to equate 1 kilogram of water with 1 L of water.