[四年级英语]conductor and capacitor-1.pptVIP

1) The parallel-plate capacitor平行板电容器 - - - - - - - - - - The E field between the plates: The potential difference between the plates: The capacitance of parallel-plate capacitor is: A: the area of the plate. d: the distance between the plates. 2) The cylindrical capacitor 圆柱形电容器 a b L The potential difference between the two cylinders: Gaussian surface From the previous result, we know: The capacitance of cylindrical capacitor is: 3) The spherical capacitor 球形电容器 Gaussian surface The potential difference between the two spherical shells: The capacitance of spherical capacitor is: Combinations of capacitors 电容器的并联和串联 1) Parallel combination 并联 The maximum charges on the two capacitors Q1 and Q2 The total charge Q stored by the two capacitors is: The equivalent capacitance of the two capacitors is: The equivalent capacitance of a parallel combination of capacitors is the algebraic sum of the individual capacitances and is larger than any of the individual capacitances. 并联电容器的等效电容等于这些电容器的电容的代数和，并且比单个电容器的电容都大。 2) series combination 串联 both capacitors must have the same charge Q. The equivalent capacitance of the two capacitors in series combination is: ？？？ The inverse of the equivalent capacitance is the algebraic sum of the inversed of the individual capacitances and the equivalent capacitance of a series combination is always less than any individual capacitance in the combination. 串联电容器的等效电容的倒数等于这些电容器电容的倒数的代数和。等效电容总是小于任意单个电容。 §3.3 capacitors with dielectrics 有电介质的电容器 One parallel-plate capacitor with distance d and charge Q. The potential between the plates is V0 d If fill some uniform dielectric into the two plates, keep the distance and the charge unchanged. The potential is found to be The capacitance of the capacitor with the dielectric is: C0 is the capacitance of the capacitor without dielectric. will change with different dielectrics. is a physical quantity to describe the electrical prope