Formula for Intensity
vs. m:
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With mathematics which we won’t derive
here, you can show this is equivalent to the equation:
This
second equation is easy to use on a calculator.
If you remember that log( 10n ) = n, for
example
log( 104) = 4,
log (105) = 5,
log(106) = 6,
you can use it even without a calculator.