# Hw1 - Homework set#1 ECE112 Note In the following questions the assumption is that the appliance or device operates until the last coulomb is used

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Sheet1 Page 1 Homework set #1 ECE112 Note: In the following questions, the assumption is that the appliance or device operates until the last coulomb is used. 1. A camcorder battery is rated at 6V with 1 Ah (Amp Hour) capacity. a)How many coulombs of charge are stored in the battery when fully charged? b)The camcorder consumes 500mA of current from the battery. How long will it run assuming the battery is initially at full charge? Ans: 3600C, 2hr 2. You have a flashlight which gets accidentally turned on inside your backpack. When on, the flashlight draws 500mA from its 3 AH cells. When you pull the flashlight out to use it, the light goes out in 30 minutes. How long was the light on inside your backpack? Ans: 5.5hr 3. As a joke, your wisecracking buddy shorts out your spare pacemaker battery by placing a paper clip across the battery terminals for 10 minutes. While shorted, 150mA of current flows through the paper clip. The battery manufacturer claims that their batteries can deliver 1mA for 200 hours. The pacemaker draws 50uA while operating. a)How much (in percentage) of the initial charge is left in the battery after the prank? b)If the spare pacemaker battery is installed, how many days do you have before the ambulance arrives for you? Ans: 87.5%, 145 days 4. Your laptop computer runs for 45 minutes before its batteries are exhausted. While running, the computer draws 350mA. a)What is the Amp Hour rating for the battery? b)When fully charged, how many coulombs of charge are inside the battery? Ans: 0.2625AH, 945C 5. While watching the double feature with his gal at the drive-in theater, Sam leaves the radio in his '57 Chevy on. The radio consumes 1A of current. To save enough money for the movie, Sam decided not to replace his old battery which has only 20,000 coulombs of charge left. Starting the car engine will require 6000 coulombs of charge. The double feature lasts 4 hours. a)Will Sam be able to start the car after the movie?

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## This note was uploaded on 04/17/2010 for the course ECE 112 taught by Professor Traylor during the Winter '09 term at Oregon State.

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Hw1 - Homework set#1 ECE112 Note In the following questions the assumption is that the appliance or device operates until the last coulomb is used

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