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dB

ValeryOchkov
24-Ruby IV

dB

It is necessary to express the power of the power plant in decibels.
I go online and find out that bel is the decimal logarithm of the ratio of two physical quantities, the second of which (the denominator of the fraction) is called a certain base. In the same place on the Internet you can find the corresponding formula for the calculation.
Here's how such a calculation might look like in Mathcad 15 with the help of tools for separating variable and function names into styles using different font colors (black, green, blue and white - invisible).
If one watt is taken as the base, then the power of the largest Russian thermal power plant, Surgutskaya GRES-2, will be 96.812 decibels (see please the picture and the attach).

dB-1.png

We solve the inverse problem: given the power in decibels, it is necessary to calculate the power in the usual watts.

dB-2.png

Question. Why are decibels called decibels and not decabels? After all, if we multiply the logarithm by ten, and not by one tenth.

 

See please also decibel 

 

6 REPLIES 6
LucMeekes
23-Emerald III
(To:ValeryOchkov)

Answer is simple.

How do you get from 1 metre to decimeters? By multiplying the amount in metres with 10.

1 m = 10 dm

likewise:

1 B is  10 dB

 

Success!
L:uc

Thank you Luc  for lifting a burden from my soul!

But

1 dB is 0.1 B

LucMeekes
23-Emerald III
(To:ValeryOchkov)

Correct.

1 db = 0.1 B

Multiply each side of the equation with 10, you get:

10 dB = 1 B

Thus: 1 B is 10 dB.

 

Success!
Luc

1 db = 0.1 B

Multiply each side of the equation with 10, you get:

10 dB = 1 B

Thus: 1 dB is 0.1 B or 1 dB is 0.1 log(var/base) not 1 dB is 10 log(var/base)

 

 

Cut me into pieces, eat me with butter, but if I want to get a decimeter, I divide the meter by 10, not multiply the meter by 10. If I multiply the bel by ten, then I get a decabel, not a decibel.
Cut me into pieces, eat me with butter!

 

LucMeekes
23-Emerald III
(To:ValeryOchkov)

Correct, if you want to get a decimetre, you divide the metre by 10, That is answering the question: How long is a decimetre?

 

BUT.

 

If you have a rope with a length of 100 cm, then its length is 1 m, or 10 dm. That is: to express the length in dm instead of in m, you have to multiply the value in front of the metre with 10 and replace the m with dm.

 

Remember where we came from. You (implicitly) asked the question: if we want to express a ratio in dB (instead of B), why do we multiply with 10 (instead of dividing by 10).

 

Success!
Luc

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