Question
MasteringPhysics: CH25 HWI-GoogleChrorne Secure https:/ session masteringphysics.com/myct itemView assignmentProblemID-873 CH25 HW Exercise 25.25 previous 4 of 4 return to assignment Exercise 25.25 Part A A copper transmission cable 180 km long and 12.5 cm in diameter carries a current of 130 A What is the potential drop across the cable? V= 32.8 V Submit My Answers Give Up Correct Significant Figures Feedback: Your answer 32.9 V was either rounded differently or used a different number of significant figures than required for this part. Part B How much electrical energy is dissipated as thermal energy every hour? E7195 Submit My Answers Give Up Incorrect: Try Again; 15 attempts remaining Continue ype her
Explanation / Answer
here,
length of wire , L = 180 km = 1.8 * 10^5 m
diameter , d = 12.5 cm
radius , r = 6.25 cm = 0.0625 m
the resistance , R = p * l /area
R = 1.72 * 10^-8 * 1.8 * 10^5 /( pi * 0.0625^2) = 0.252 ohm
for t = 1 hr = 3600 s
the energy disspated , E = I^2 * R * t
E = 130^2 * 0.252 * 3600 J
E = 1.54 * 10^7 J