UNIVERSITY OF CALIFORNIA AT BERKELEY EECS Department EECS 40 Fall 2007 Prof Chang Hasnain Homework 2 Due at 5 pm in 240 Cory on Wednesday 9 12 07 Total Points 100 Put 1 your name and 2 discussion section number on your homework You need to put down all the derivation steps to obtain full credits of the problems Numerical answers alone will at best receive low percentage partial credits No late submission will be accepted expect those with prior approval from Prof Chang Hasnain Problems of this HW are from Hambley 4th Edition 1 P2 50 Node Voltage Analysis 8 points Just writing a system of equations in standard form is sufficient you don t need to solve them 2 P2 60 Node Voltage Analysis with dependent source 10 points 3 P2 62 Mesh Current Analysis 10 points Just writing a system of equations in standard form is sufficient you don t need to solve them 4 Circuit with many sources Superposition Power 9 points a Use superposition to find the current i 7 points b How much power does R1 absorb 2 points 5 P2 79 Thevenin Norton equivalent 12 points 6 P2 83 Thevenin Norton equivalent with dependent source 14 points 7 P2 103 Wheatstone Bridge 2 points 8 P2 104 Wheatstone Bridge 10 points 9 P1 24 Power Energy 5 points 10 Measuring Power 20 points Consider the following circuit in which you want to calculate the power absorption of resistor R Page 1 of 2 UNIVERSITY OF CALIFORNIA AT BERKELEY EECS Department a Assume you do not know the exact values of Rs and Vs but R is known to be 10 The ideal amperemeter measures a current of 1 A What is power absorption of R 2 points b For the following R will be considered To measure the power absorption we add an ideal voltmeter to the circuit The voltmeter measures 5V and the amperemeter measures 4 A What power is absorbed by the resistor 2 unknown points c Now neither the amperemeter nor the voltmeter are ideal any longer The amperemeter can be modeled as an ideal amperemeter in series with resistor RA the voltmeter as an ideal voltmeter in parallel with resistor RV Therefore we get the following circuit The power absorption of R will change slightly due to the addition of the two new resistors Suppose we do not mind this effect but do wish to correctly compute the new power absorption Which of the measuring instruments does not measure the right value for calculating the new power absorption of R Why 4 points d Under the assumption that you know R and RV can you correct the discrepancy How 7 points e Rearrange the measurement setup so that the measuring instrument you found in c to measure the wrong value is now measuring the right quantity What is the problem of this setup 5 points Page 2 of 2
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