6Lab 3: Passive ComponentsU.C. Davis Physics 116A10/8/2003INTRODUCTIONIn this lab you will build a Théveninequivalent circuit and a low-pass filter and willcharacterize each.1. THÉVENIN EQUIVALENT CIRCUITIn this section, you will build a circuit andits Thévenin equivalent and see how equivalentthese two circuits really are. Construct thecircuit shown in figure 1, a voltage divider withload resistance, RL. For your lab report,calculate and measure the voltage at pointV fortwo values of RL, 1kW and 10kW. Be sure toinclude uncertainties in your measurements andto discuss the agreement between the calculatedand measured values.+R = 1k15VLW4.7k2.7kWWVFigure 1: Circuit for demonstrating Thévenin equivalent.Now calculate the r and e for the Théveninequivalent of the above circuit. The Théveninequivalent circuit is shown in figure 2.Construct this circuit using the variable voltagepower supply for e and some combination ofresistors for r. For your report, show yourThévenin calculation, measure your actual e, r,and voltage at V, and compare V with the circuitabove and with theory.+= 1kreLWVRFigure 2: Thévenin equivalent for circuit of figure 1.2. LOW PASS FILTERIn this section, you will measure thefrequency response of a low pass filter circuit andsee what the "low pass" name refers to.Construct the circuit shown in figure 3 using thefunction generator as the AC source. Use a 10Vpeak to peak sine wave as the vin source signal.Use both channels of the oscilloscope to monitorVin and Vout simultaneously showing theirphase relationship as follows. Connect Ch. 1 toVin and Ch. 2 to Vout. Set the oscilloscope totrigger on Ch. 1 only and adjust the trigger leveluntil the trace starts at zero with positive slope.Ch. 1 will now display a sine wave. The phasedifference of Ch. 2 will now be evident throughthe different starting value its trace and theoverall displacement of the Ch. 2 waveformrelative to Ch. 1.~~2.7 kW0.1 mFVou tVinFigure 3: Low pass filter circuit.7The input and output signals can now beexpressed as:Vin(t) = vinmsin(wt),Vout(t) = voutmsin(wt +f),where vinmand voutm are the amplitudes of theinput and output waveforms, respectively. Calculate the break frequency (or cornerfrequency) fb b2=w p for this circuit. Use thisfrequency and select 10 other frequencies, 5 abovefb and 5 below fb. For each frequency, measurethe voltage gain, Av=voutmvinm,and the phase shift, f , of Vout relative to Vin.Bear in mind that you will want to find the slopeof the fall-off of the gain on the log-log plot athigh frequencies.For your lab report, include your fbcalculation, your gain and phase shift data, and 4separate graphs of the data. First, make a linear-linear graph of gain vs. frequency and phase anglevs. frequency, indicating fb on each. (That's 2graphs.) Then, make a log-log plot of gain vs.frequency and a semi-log plot of phase angle(linear) vs. frequency (log), comparing the data tothe theoretical Bode plots for gain and phaseangle. (That's the other 2.)3. HIGH PASS FILTERDesign an RC high-pass filter withfbkHz= 10. Build it and take enough data tomake Bode plots for gain and phase. For yourreport, include a description of how you designedthe circuit and the two Bode plots (each of whichincludes data points and a theoretical