PHY 2054 Midterm: 2054_Spring12_Exam2-solutions
Document Summary
Exam 2 solutions: a portable cd player does not have a power rating listed, but it has a label stating that it draws a maximum current of 159. 0 ma. The player uses four 1. 50 v batteries connected in series. Solution: the power is given by p = ei = 6 ! 0. 159 = 0. 954 w: a galvanometer has a coil resistance of 48. 0 . Solution: we want the current to be 0. 120 ma when the galvanometer is placed across a 100 v. "4 = 833,000# = 0. 833m# , including the source. Thus the total resistance must be 100 / 1. 2 ! 48. 0 resistor, which can be neglected: three resistors, r1 = 4. 0 , r2 = 3. 0 , and r3 = 2. 0 , are connected in series to a 9. 0 v battery. Solution: the total current is in the series circuit is 1 a, so the power dissipated in r2 is.
