Go To Concept Tutoring Home    www.tutor45.com

 

LOGARITHMIC SCALES

 

RICHTER SCALES:

Richter Scales define the magnitude of an earthquakes:


I:  Intensity of earthquake
I0:  Intensity of reference earthquake
M: Magnitude of the earthquake, Richter number, Richter magnitude

 

SOUND INTENSITY LEVEL:


I:  Intensity of sound (W/m2)
I0:  Reference sound intensity, Intensity of sound at the threshold of hearing: I0 = 10-12 W/m2)
L:  Loudness of the sound, sound intensity level: dB
1 bel = 10 dB

Threshold of hearing is the minimum intensity detectable by the human ear.  Loudness of sound at the threshold of hearing is equal to zero dB.  Threshold of pain is about 120 dB.

 

pH SCALES:

pH = - log [H+]

pH: Acidity or alkalinity of liquid, pH level, rangers form 0 to to 14

[H+]:  Hydrogen ion concentration, number of moles of hydrogen ions per litre (mol/L)

pH = 7 for distilled water
pH < 7 for an acidic solution
pH > 7 for a basis solutions (alkaline)

1 mol = 6.02 x 1023 molecules (Avogadro number)