EXAM 2 November 6, 1987 PS 208 If you need a constant not given here or do not understand a problem, please ask me about it. No notes, books, etc. may be used during this exam. 2 -19 g = 9.8 m/sec e = 1.6 x 10 C 9 2 2 1/(4 pi epsilon ) = 9.1 x 10 N m / C 0 -7 mu / (4 pi) = 10 T m/ A 0 -31 The mass of the electron is 9.11 x 10 kg. 1. Four equal point charges Q are placed at the four corners of a square of side a . Find V at the center of the square. 2. A battery with EMF V and internal resistance r is connected across a single resistor of resistance R . For what value of R will the power dissipated in the resistor be a maximum? What will the maximum dissipated power be? 3. (From homework) Determine the current through each battery in the --------V---r------- figure. Note that the values of the | | batteries and resistances have been R1 R2 changed so as to reduce the total | | number of unknown quantities. |--------V---r-------| | | (The high side of all the R1 R2 batteries is to the right.) | | ---------V---r------- 4. A capacitor is made of two concentric cylinders of length L and radii R and R , with a dielectric of constant kappa between 1 2 the cylinders. If the inside cylinder carries a charge +Q and the outside cylinder carries a charge -Q , determine the electric field in the dielectric, the potential difference between the cylinders, and the capacitance of the device. Neglect end effects.