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EE40 Summer 2011
Neel Shah
Homework 1
Due 6/29/2011
Problem 1. Voltage Source Resistance
Let's say we have a 5 volt battery that we want to use to drive a motor. We first hook up an ideal
ammeter to the (fully charged) battery to find out what its maximum current delivery can be. We get a
reading of 8 amps. What is the source resistance of the battery?
Next we hook up this battery to the motor, which requires 5 watts of power at 5 volts. Can this battery
drive the motor? Why or why not? (Hint  model the motor as a resistor. What would its value be?)
Problem 2. Wheatstone Bridge
A strain gauge is a resistor whose resistance changes based on an applied force. We wish to measure
this unknown resistance using a wheatstone bridge circuit, shown below. The circuit is powered by an
ideal 10 volt battery and an ideal voltmeter is placed in the middle of the circuit. The voltmeter output
will change based on the unknown resistance.
Express the voltmeter reading v
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This note was uploaded on 09/09/2011 for the course EECS 40 taught by Professor Changhasnain during the Summer '08 term at University of California, Berkeley.
 Summer '08
 ChangHasnain
 Volt

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