Capacitors in Parallel

Chapter 3.12 Capacitors in Parallel

Fundamental Electrical and Electronic Principles Third Edition Book
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Fundamental Electrical and Electronic Principles Third Edition Book

  • Electric Fields and Capacitors 87 Worked Example 3.8 Q A p.d. of 180 V creates an electric fi eld in a dielectric of relative permittivity 3.5, thickness 3 mm and of eff ective csa 4.2 cm 2 . Calculate the fl ux and fl ux density thus produced. A V 180 V; d 3 10 3 m; εr 3.5; A 4.2 10 4 m 2 There are two possible methods of solving this problem; either determine the capacitance and the use Q VC or determine the electric fi eld strength and use D ε o ε r E . Both solutions will be shown. CAdCεεor faradso pF 8 85403 54 2030434243....1111aand since coulomb thenhence, QVCQQ111804 3400782..nnC Ans DQAD coulomb/metreso C/m 204278042086...1111Ans Alternatively: EEEVdD volt/metreso kV/m and using couor118030603εεllomb/metreso C/m 22328 85403 560086DDQDA...1111Ans coulombso nC 111...8604 2007864QAns 3.12 Capacitors in Parallel Consider two capacitors that are identical in every way (same plate dimensions, same dielectric material and same distance of separation between plates) as shown in Fig. 3.8 . Let them now be moved vertically until the top and bottom edges respectively of their plates make contact. We will now effectively have a single capacitor of twice the csa of one of the original capacitors, but all other properties will remain unchanged. Fig. 3.8