I was trying to figure out how to solve a decibel problem. I have been out of school for a very long time and my math is very rusty. Here is an example of the problem:
If an amplifier turns a 5watt signal into a 25watt signal thats a gain of ?
The equation is: 10xlog10(25/5)=10xlog10(5)=10x0.7=7db
now my question. I can easily solve this problem using the log function of my calculator but solving it without a calculator has evaded me. I find that log10=1 but then were did the 0.7 come from. I have attempted to look up the mantissa but I either cannot find the right one in the chart or I am looking for the wrong thing. Can someone show me how to determine the answer of this problem without a calculator.
I would also appreciate information on how to use antilogs as well. I believe the antilog is -1 while the log is 1 am I right thanks WMC
