# Electrical Engineering - Passive Filters - Discussion

### Discussion :: Passive Filters - General Questions (Q.No.16)

16.

At a certain frequency, the output voltage of a filter is 6 V and the input is 12 V. The voltage ratio in decibels is

 [A]. 6.02 dB [B]. –6.02 dB [C]. 12.04 dB [D]. –12.04 dB

Answer: Option B

Explanation:

No answer description available for this question.

 Jill Scar said: (Oct 10, 2015) Why is it negative?

 Pavithra said: (Oct 14, 2015) Always the ratio is first output voltage (6) then input voltage (12) that's why it is negative.

 Shan said: (Nov 27, 2015) Wrong @Pavithra that negative due to we convert into the decibel scale.

 Sudhir said: (Apr 11, 2016) Use this formula to convert the voltages to decibels: 20 * Log (Vout / Vin) = dB.

 Shafi said: (Mar 14, 2017) How to calculate decibel values without calci? Can anyone suggest me.

 Suma said: (Jun 12, 2017) Here, 20log(Vout/Vin) = 20log (6/12) = -6.02dB.

 Sushma said: (Jun 27, 2019) Please, can anyone tell how to calculate dB and why it is negative?

 Majid Mahmood said: (Aug 19, 2019) Db = 20logvout/vin so 20(log6/12) = 20 * (-0.3010) = -6.02db.

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