Question

EE 282-Circuit I Pre-Lab 9 Maximum Power Transfer Theorem Name Concepts: In this pre-lab we will be leaming about Maximum Power Transfer Theorem. Maximum power is transferred to the load when the load resistance equals the thexenin equivalent, and we carry out the analysis using Thevenin's equivalent circuit. In order to do this, first build the following circuit on Mutism. 1 R1 5.1k0 R3 2 V1 R2 8kQ 6.8㏀ Fig. 1 Part 1: To find the Thevenin equivalent resistance, we first calculate the voltage across the circuit leaving the output terminals open as shown in Fig. 2 below. This is the Thevenin equivalent voltage. With the Multi-meter set to V, we measure the voltage and fill Table 1 for V. R1 R3 2 5.1kQ V1 R2 6.8k0 Fig. 2 We then calculate the current through the terminal a-b by short-circuiting the terminals. This current is then divided into the voltage to give the Thevenin equivalent resistance or Rn. With the Multi-meter set to A, we measure the current and fill Table 1 for ls Note that we insert very small resistor, for instance 10Ω, for measurement accuracy. Table 1 Calculated Measured th Then, we determine the Thevenin equivalent resista nce using The thexenin equivalent resistance for the circuit given in Fig. 1 is Part II: Now we see if the load resistance determined above in Part I maximizes the power across Ru. For this, we add a variable load resistance across the output terminals, and power delivered to the load resistance for various Ri values that are listed in Table 2. Note that we use wattmeter to measure the power. States) Table 2 PRI. Ru 聾1 10% 50% Rih 100% Rib 150% 200% Bn. 300% Plot PRu. versus Ri below and indicate the point at which maximum power transfer is attained Part III: The Thevenin equivalent circuit works with AC as well as with DC. Measuring the Thevenin equivalent voltage is done easily enough. However, an oscilloscope can't measure current. Measuring the short circuit current cannot be done and thus we must come up with a different way to get the resistance. Consider the circuit below: xsci XFG1 Requivalenti R7 In this circuit if R7 (the load resistance) is set equal toivales then the voltage measured on channel B of the oscilloscope will be one half of the input voltage (you can verify this using the voltage divider equation. Build the following circuit XSc2 XFG2 R9 R6 3k0 Rload R8 Set the function generator to 1 kHz and an amplitude of 12V. Let Rlod- 10 M ohms. Use the oscilloscope channel B to find the Thevenin equivalent voltage. Now, adjust Rio until the output voltage is one half of the Thevenin equivalent voltage. The value of Rload is now equal to the Thevenin equivalent resistance. Vth United States)

Answer 1

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