pre cal problem help please?
noise from ,mower measured at 102db. noise from music concert measured at 122 db. find ratio of intensity of rock music to mower
if possible explain how
thanks
Decibals are the preferred unit of measurement for intensity of sound, electric power, and comunications signal strength. The decibal (db) is logarithmic and is usually compared to some base level. Therefore, each measure in db is a ratio all by itself. The way the formula goes is:
i = 20*log10(P / Pb)
where Pb is ths power at the base level.
(sometimes, the formula is 10*log10(P/Pb), depending on the usage)
Furthermore, since db's are logarithmic, you can't just divide them to get any meaningful number. You must add/subtract them:
In the case of the stated problem:
i1 - i2 = 122 db - 102 db = 20 db
20*log10(P/Pb) = 20
log10(P/Pb) = 1
P/Pb = 10
Therefore, the music concert is 10 times more intense than the lawn mower.
