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Unformatted text preview: ate of flow of charge and voltage is the measure of the energy transferred per unit of charge, product of current and voltage is the rate of energy transfer (power). Power = Voltage x Current: p vi The physical units of voltage times current is : volts x amperes = (joules/coulomb)x(coulomb/sec)=joules/sec=watts (W). Energy absorbed by the element is: t2 w p (t )dt which is in joules. t1 The passive sign convention When positive charge enters an element at the positive voltage terminal and leaves the negative voltage terminal, then the positive charge loses energy. In this case, the element is said to have absorbed the energy. Such elements are said to be passive elements. The current always enters the positive voltage terminal for passive elements. While solving circuits, we need to assign voltage and current variables for each element, sometimes without any prior information about them. In such cases, we can assume them to be passive elements and assign the current variable to be entering into the positive terminal of the voltage variable. This assign...
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This document was uploaded on 01/20/2014.
- Winter '14