A logarithmic scale is a nonlinear scale used when there is a large range of quantities. Common uses include the earthquake strength, sound loudness, light intensity, and pH of solutions.

A logarithm is an exponent (power) to which a base number must be raised to yield the same result. The standard logarithm scale is called **base 10. **The term “log” is used when specifying a log scale.

In base 10, the log of 100 = 2:

When basing your equation on base 10, indicating the base is not required as base 10 is implied:

Other bases can be used, such as base 2, or base 3, or even base 25:

The reason for using a log scale is so we can evaluate our data easier. For example, a chart of data can either look like a boring straight line, or with a log system applied, a more dynamic chart is created:

The graph above is nothing in particular, but the blue line will be raw data, and the pink line will be the same data using a base 10 log scale.

What is a good example of a logarithm scale?