Discussion in 'Homework Help' started by catch3624, Oct 7, 2009.

1. ### catch3624 Thread Starter New Member

Oct 7, 2009
3
0
Hello people...These problems been troubling me now for days...I need to find out if a signal has passed through three cascaded amplifiers, each with a 4 dB gain. What is the total gain? And how much was the signal amplified?
Also a signal has a wavelength of 1 Micrometer in air. How far can the front of the wave travel during 1000 periods? Can anyone please help me or give me advice as to where to locate this information.

Last edited: Oct 7, 2009
2. ### Audioguru New Member

Dec 20, 2007
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895
Each amplifier adds a gain of 4dB. Look on a graph to see how much is a gain of 4db times the quantity of amplifiers. Or calculate it.
What is the speed of sound? Then calculate how far the sound goes in 1 micrometer times 1000.

3. ### catch3624 Thread Starter New Member

Oct 7, 2009
3
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Do you mean that I could add up each 4dB gain which would total 12dB or is there a formula that I must use? And the speed of sound is 344 m/s but a micrometer is = to 1 x 10^-6. How would/should I calculate this then? And by the way, Thanks for the reply.

4. ### JDT Well-Known Member

Feb 12, 2009
658
85
12dB ( = 4dB + 4dB + 4dB)

12dB ( = 4x)

1mm

The speed of sound in air is not important as you have already said that 1 wavelength = 1um. So, in 1 period of the signal it has travelled 1um. We don't know the period but 1000 periods will be 1000 times longer so will travel 1000 times further.

5. ### catch3624 Thread Starter New Member

Oct 7, 2009
3
0
The response have been great. Now I can combine it with what I have already learnt and done, I will be able to come to the best conclusion. Thank you.