Answer Happy

TABLE 13,3 100 Fle144) 47 0 100 (Norton Eq) (Norton Equi 12V VA 12V 1.1.4 How do the calculated (part 2(e)) and measured values of I compare? The values of In are within reason. (e) The level of ly can be determined by replacing the 47-resistor by a short cir cuit and measuring the short-circuit current. Since the internal resistance of an ammeter i relatively low, this can be accomplished by removing the 47-resistor and replacing it with the ammeter section of the DMM. Since the curent level is unknown, start with the highest scale and work down to the scale that provides the highest degree of accuracy. Record the level of in the second column of Table 13.2. How does the calculated value of I, from part 2) compare with this measured value of Iy? 275 hit reason ( Ry is now determined experimentally by first calculating 1y/2 using the measured value from part 2(e). For the Norton equivalent circuit with R = R. L = 1./2. IN Connect the 1-1 potentiometer and ammeter in a series configuration betwech points a and b, as shown in Fig. 13.4(b). Turn on the supply and vary potentiometer til the ammeter reading is lw/2. Then remove the potentiometer and measure Ry and record in Table 13.2 How does the calculated value of Ry from part 2(b) compare with this mcasured half the inte value of Ry? Its (8) Construct the Norton equivalent circuit defined by the calculated levels of Rwand 1x from part 2(b). First construct the network of Fig 13.5. a gora zura
101 (DMMD 1-1 (part 2) (Start with highest scale) 12099 FIG. 13.5 Vary the supply voltage until the DMM indicates the value Ifrom part 2(b). Record the values of E and I in Fig. 13.6(b). Next remove the DMM and, using it as an ohmmeter, set the 0-1-k potentiometer to the value of Ry from part 2(b). Now insert the 0-1-1) potentiometer in the circuit of Fig. 13.6(b). Equivalent 14 10kΩ 470 IN wi, 470 62.824 1-potentiometer sto R214 Norton equivalent circuit (a) Nonne equivalent circuit (b) FIG. 13.6 The network of Fig. 13.6(b) is the Norton equivalent circuit. The 0-1-kn potentiometer is equivalent to Ry, and the 10-k resistor in series with the power supply is the equivalent current source. The 10-k resistor was chosen to ensure minimum sensitivity on the part of Iy to the smaller resistor values connected in parallel in Fig. 13.6(b). In other words, ly = EX10 kn + R) E/O kA and, therefore, approximates an ideal current source. Measure the voltage and compute I, using the measured resistor value and record in the second column of Table 13.3. Calculation: How does the level of l, determined here compare with the calculated level of part 2(c)? Has the Norton equivalent circuit been verified?
EXPERIMENT de 64 () Replace the 17-resistor of the 13.6%b) by a 100-resistor and measure the wolte. Calculate the resulting currently with the measured resistor value. Recond the results in the third column of Table 13.3 Calculation: Reconstruct the network of Fig. 13.4 with Re - 1000 and measure the voltage Calculate the current using the monsured resistor value and record all results in the last column of Table 13.3 Calculation: How do the levels of l for this part compare? Have we verified that the Norton equiv. alent circuit is valid for changing loads across its terminals? Part 3 Source Conversion (a) Using source conversion techniques, the Norton equivalent circuit of Fig. 13.6(b) can be converted to a Thevenin equivalent circuit. Further, if the circuits are completely equiva lent, the measured values of V, and I should be the same as before. The conversion can be accomplished by first calculating the Thevenin voltage E Determine Es using the version equation Enly and the parameters of Fig. 13.6(b). n = / .4.08V En Since Rys - the Thovenin equivalent circuit can now be constructed.
165 NORTON'S THEOREM AND CURRENT SOURCES (b) Construct the Thevenin equivalent circuit of Fig. 13.7 0-1-20 potention Power supply set to E- x R FIG. 13.7 Thevenin equivalent circuit Now measure the voltage Vis and again compute (Use the measured value of the 47-resistor. Record in Table 13.4. Calculation: How do V, and I, compare to those in part 2(d)? Calculate the percent difference from Part 2/d) - Part 3(b) Part 2) X 1005 Difference and record in Table 13.4. Calculation: 00254 0.276 x 100% 10.25A TABLE 13.4 Difference Measured V.
161 NORTON'S THEOREM AND CURRENT SOURCES Part 2 (b) Using measured resistor values, calculate the levels of sand for the network to the left of the 47. resistor and record the results in the first column of Table 13.2. 2.10 3. wa El IN=I. 3900 550.A2204 Bithe k2,6 =3001 220 732 2 1320 (3.49 465) See 7502 Rothy 30th 2-3 7.5 IN = 2.094.A AL 8132 300:- TRA 7720 RN=5204 3.58347574 -3.490 ( Using the Norton equivalent circuit calculated in part 2. calculate the current I for a load of 470 3474 Calculation: It - In 500 2047 4 = 1.910A In = 1.910A TABLE 13.2 Calculated by Mere & 5200 2.094nA (d) Turn on the supply of Fig 13.4 and measure the voltage The calculate the current losing the measured value of the 47 n resistor. Record both values in the first column of Talle 13.3 Calculation: IL-E 124 H 474 Ic= 0.25A