Physics for Scientists and Engineers II, Summer Semester Lecture 10: June 12 th 2009 Physics for Scientists and Engineers II

Physics for Scientists and Engineers II, Summer Semester RC Circuits RC Circuits: Circuits containing Resistors and Capacitors. In such circuits, the current(s) may not be constant. + -

Physics for Scientists and Engineers II, Summer Semester Charging the Capacitor Apply Kirchoof’s loop rule:

Physics for Scientists and Engineers II, Summer Semester Solving the Differential Equation

Physics for Scientists and Engineers II, Summer Semester Getting the current t q(t) t I(t)

Physics for Scientists and Engineers II, Summer Semester The time constant  of the RC circuit

Physics for Scientists and Engineers II, Summer Semester Measuring the time constant t V c (t) t I(t)

Physics for Scientists and Engineers II, Summer Semester Discharging the Capacitor Apply Kirchhof’s loop rule:

Physics for Scientists and Engineers II, Summer Semester Solve….

Physics for Scientists and Engineers II, Summer Semester Discharging the Capacitor…the way Serway does it Apply Kirchhof’s loop rule:

Physics for Scientists and Engineers II, Summer Semester Solve….

Physics for Scientists and Engineers II, Summer Semester Example: Problem 31 in the book 10V 1.00  4.00  8.00  2.00  1)For long time: What is V c ? 2)For long time: What is Q c ? 3)If battery is disconnected from the circuit, over what time interval does the capacitor discharge to one-tenth of it’s initial voltage? 1.00  F 1) For long times, the current I c =0 (no more charging or discharging). 10V IcIc a b

Physics for Scientists and Engineers II, Summer Semester Example: Getting Voltage over Capacitor 10V 1.00  4.00  8.00  2.00  ab

Physics for Scientists and Engineers II, Summer Semester Example: Discharging without Battery 1.00  4.00  8.00  2.00  1.00  F 6.00  9.00  1.00  F 3.60  1.00  F

Physics for Scientists and Engineers II, Summer Semester Magnetic Fields

Physics for Scientists and Engineers II, Summer Semester Magnetic Fields and Forces N S