An application of the tangent and normal lines in AC circuits:
Bandwidth of a Series Resonance Circuit
Series Resonance circuits are one of the most important circuits used in electrical and electronic circuits. They can be found in various forms of applications such as AC mains filters, noise filters and also in radio and in the past, television tuning circuits producing a very selective tuning circuit for the receiving of the different frequency channels.
Given a curve that maps Current versus frequency, the tangent line that has a slope of zero represents the current maximum IMAX and the horizontal line that goes through the inflection points reveal the values of the lower and upper frequencies at – 3dB or 0.707 IMAX
Further, the line of symmetry that goes through f r is normal to the tangent line at IMAX and the two parallel normal lines at f L and f H help to determine the frequency difference which is called the Frequency bandwidth.
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above, find the maximum current, the inflection points, then give the equation of the vertical
lines that go through each inflection point.Determine the band width. Round all values to the 100ths
xmin= -2,xmax = 3,ymin= -2,ymax = 3
