PHY 2054 Midterm: 2054_Spring13_Exam2_Solutions
Document Summary
Exam 2 solutions: a voltage surge produces 140 v for a moment in a standard 120 v line. Thus if only the voltage changes, the power scales by. P: a 105 f capacitor supplies 17 j of energy to an electronic flash. Solution: the current falls according to i = i. Here we are told that the current falls to. 35% of its initial value in 1. 4 msec, so e. Solving yields r = 12. 7 : a 2. 00 kw heating element from a hair drier designed to operate at 120 v has a length of 80. 0 cm. A 10. 0 cm section of the element is removed. Solution: the new resistance is 7/8 of the original resistance because the heating element is 7/8 of its original length, assuming uniformity of the material. The power dissipated is then new = i!v = v.
