1. LECTURE 11 Pick up reading quiz #2 lecture notes for Lecture 11 Course questionnaire Pick up reading quiz #2 lecture notes for Lecture 11 Course questionnaire

2. Combinations of Capacitors: Basic Rules (a)Parallel Capacitors (b) Series Capacitors

3. Exercise: Calculate the effective capacitance for the following network

4. Consider two capacitors, each having plate separation d. In each case, a slab of metal of thickness d/3 is Inserted between the plates. In case (a) the slab is not connected to either plate. In case (b), it is connected to the upper plate. The capacitance is higher for 1.case (a). 2.case (b). 3.The two capacitances are equal (a)(b) Capacitor plates Metal slab d d/3 Equivalent with 2 capacitors in series, with magnitude 3C 0 Just a single capacitor with magnitude 3C 0

5. Insert dielectric Dielectrics in electric field

6. A dielectric is inserted between the plates of a capacitor. The system is then charged and the dielectric is removed. The electrostatic energy [U=(1/2)CV 2 ] in the capacitor is 1.greater than 2.the same as 3.smaller than it would have been if the dielectric were left in place. + + + + + + + + + + + + + - - - - - - - - - + + + + + + + + + + + + + Charges on the capacitor plate (blue) are attracted to the bound surface charges of the dielectric. Work must be invested to remove the dielectric, and this work is stored as electrostatic energy. Another way: as the dielectric is removed, k=1: U increases