78CHAPTER 17 17.16We assume that your hair dryer will use about 400 W of power for 10 minutes each day of the year. The estimate of the total energy used each year is ()( )()min1 hr0.400 kW10 365 d24 kWhd60minEt=∆==PIf your cost for electrical energy is approximately ten cents per kilowatt-hour, the cost of using the hair dryer for a year is on the order of $24 kWh0.10 $2.4 or ~$1kWhcostErate=×==17.17The resistance is 9.11 V0.253 36.0 AVRI∆===Ω, so the resistivity of the metal is ( )( )223840.253 2.0010m1.5910m450.0mRdRALLππρ−−⋅Ω×⋅==×Ω⋅Thus, the metal is seen to be silver . 17.18With different orientations of the block, three different values of the ratio
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