Question
Sun March 08, 2015 By: Ritu Nathawani

1. a capacitor has been charged by a DC source. what are the magnitudes of the conduction and displacement currents, when it is fully charged?
2. two wires of equal lenght, one copper and the other of manganin have same resistance. which is thicker?
 

Expert Reply
Jyothi Nair
Sun March 08, 2015
Given that the capacitor is fully charged, This implies that the it maintains a constant voltage V and the charge q will also be a constant.
begin mathsize 14px style Electric space flux space through space the space plates space of space straight a space capacitor space is space given space by space straight ϕ space equals straight q over straight epsilon subscript 0 Conduction space current comma space straight I subscript straight C space equals straight C dV over dt As space straight V space is space straight a space constant comma space dV over dt equals 0 rightwards double arrow space straight I subscript straight C space equals straight C dV over dt equals 0 bold i bold. bold e bold. bold space bold Conduction bold space bold current bold comma bold space bold I subscript bold C bold space bold equals bold 0 bold space bold when bold space bold fully bold space bold charged and space Displacement space current comma space straight I subscript straight D space equals space straight epsilon subscript 0 dϕ over dt straight I subscript straight D space equals space straight epsilon subscript 0 fraction numerator straight d open parentheses straight q over straight epsilon subscript 0 close parentheses over denominator dt end fraction As space straight q space is space also space straight a space constant comma space straight d open parentheses straight q over straight epsilon subscript 0 close parentheses equals 0 rightwards double arrow straight I subscript straight D space equals space straight epsilon subscript 0 fraction numerator straight d open parentheses straight q over straight epsilon subscript 0 close parentheses over denominator dt end fraction equals 0 bold i bold. bold e bold. bold space bold Displacement bold space bold space bold current bold comma bold space bold I subscript straight D bold space bold equals bold 0 bold space bold when bold space bold fully bold space bold charged end style
 
Please ask the other question as a seperate query
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