![]() In other words, a circuits overall gain ( dB), or attenuation (-dB) is the sum of the individual gains and attenuations for all stages connected between the input and output.įor example, if a single stage amplfier has a power gain of 20dB and it supplies a passive resistive network that has an attenuation of 2, before the signal is amplified again using a second amplifier stage with a gain of 200. One of the advantages of using the base 10 logarithm ratio of two powers is that when dealing with multiple amplifier, filter or attenuator stages cascaded together, we can simply add or subtract their decibel values instead of multiplying or dividing their linear values. So the result is 100mW as declared in example No1. So if we use the logarithmic ratio of two quantities, P 1 and P 2 we end up with a new quantity or level which can be presented using Decibels. When analysing circuits in the frequency domain, it is more convenient to compare the amplitude ratio of the output to input values on a logarithmic scale rather than on a linear scale. Remembering of course that if a circuits output is positive, then it produces amplification or gain, and if its output is negative, then it produces attenuation or loss. Likewise if we cascaded together to first-order RC filter circuits with attenuations of 0.7071 each, the the total attenuation would be 0.5 (0.7071*0.7071). ![]() For example, if we cascade two amplifier stages together with power or voltage gains of say 20 and 36, respectively, then the total gain would be 720 (20*36). When designing or working with amplifier and filter circuits, some of the numbers used in the calculations can be very large or very small. On September 21, a second earthquake occurred, this one measuring 8.1, hit Mexico City.Generally, decibels is a measure of loudness. On April 30, 1986, an earthquake in Mexico City measured 7.0 on the Richter scale. How many times stronger was the Alaska quake than one measuring 4.0? 34. An earthquake measuring 4.0 is consideredsmall and causes little damage. In 1964, an earthquake in Alaska measured 8.4 on the Richter scale. How much more intense are the sound waves from a vacuum cleaner than those from a refrigerator? 33. Ī refrigerator produces 50 decibels of noise, and a vacuum cleaner produces 85 decibels. How many times more intense was this than a 90-decibel sound (the threshold of pain for the human ear)? 32. Īt a concert by The Who in 1976, the sound level 50 meters from the stage registered 120 decibels. Compare the acidity of normal hair, shampoo, and conditioner. The pH of normal hair is about 5, the average pH of shampoo is 8, and 4 for conditioner. How many times more acidic is acid rain than normal rain? 30. Some areas of Ontario have experienced acid rain with a pH of 4.5. Estimate the temperatures of the events indicated. The log scale shows various temperatures in Kelvins. What was the intensity of the sound waves? Applications 19. The noise of a leaf blower was measured at 110 decibels. Find the intensity of the blue whale's whistle in watts per square meter. Its whistles have been measured at 188 decibels and are detectable 500 miles away. The loudest sound emitted by any living source is made by the blue whale. Find the decibel level for a jet airplane. Ī jet airplane generates 100 watts per square meter at a distance of 100 feet. Find the decibel level of the sound of a lawn mower. The hydrogen ion concentration of vinegar is about \(6.3\times 10^\) watts per square meter.
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