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#1
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Transposing Formulas
Can anyone help me to transpose this decibel formula, DECIBEL = V1/V2 LOG20, If I know V1 and I know the decibel I need to work out V2 .... Thanks -- Johno ------------------------------------------------------------------------ Johno's Profile: http://www.excelforum.com/member.php...o&userid=28578 View this thread: http://www.excelforum.com/showthread...hreadid=482415 |
#2
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Transposing Formulas
A little algebra:
V2 = V1/Decibel Log20 In article , Johno wrote: Can anyone help me to transpose this decibel formula, DECIBEL = V1/V2 LOG20, If I know V1 and I know the decibel I need to work out V2 .... Thanks |
#3
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Transposing Formulas
JE McGimpsey Wrote: A little algebra: V2 = V1/Decibel Log20 In article , Johno wrote: Can anyone help me to transpose this decibel formula, DECIBEL = V1/V2 LOG20, If I know V1 and I know the decibel I need to work out V2 .... Thanks Thanks but I'm not so sure this works out exactly, if I use 1OO as V1 and 50 as V2 then the decibel figure is 6.02 .... if I then work back using the formula V2 = V1/Decibel Log 20 instead of V2 equalling 50 as in the first formula it equals 6.41 not 6.02 and if other figures are substituted and then worked back the error varies .... can anyone shed some light. ... Regards -- Johno ------------------------------------------------------------------------ Johno's Profile: http://www.excelforum.com/member.php...o&userid=28578 View this thread: http://www.excelforum.com/showthread...hreadid=482415 |
#4
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Transposing Formulas
Well, it helps to start out with the right formula. Instead of
DECIBEL = V1/V2 LOG 20 the formula is actually DECIBEL = 20 * LOG(V1/V2) So, just rearranging and taking the antilog V2 = V1/10^(DECIBEL/20) In article , Johno wrote: Thanks but I'm not so sure this works out exactly, if I use 1OO as V1 and 50 as V2 then the decibel figure is 6.02 .... if I then work back using the formula V2 = V1/Decibel Log 20 instead of V2 equalling 50 as in the first formula it equals 6.41 not 6.02 and if other figures are substituted and then worked back the error varies .... can anyone shed some light. ... Regards |
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