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. 