CHAPTER 1 - Fundamentals of Electrical Circuits
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1.4 V & I or E & H ?
In this section we will explain how the values of resistance R, capacitance C, and inductance L, not
only provide a way to relate voltages and currents for resistors, capacitors and inductors but also a
link between the moduli of Electric and Magnetic fields. For the reader's convenience the classical
V-I equations for resistors (1.4-1)(a), capacitors (1.4-1)(b) and inductors (1.4-1)(c) are shown below.
( ) ( )
( )
( ) ( )
( )
( )
In the following three sections we will look at how we can approach the abovementioned circuit
elements from a field perspective.
1.4.1 Resistors
Let us now consider a simple resistor in the form a high resistance wire. This could be the filament of
a light bulb for instance (Figure 1.4-1) but also a heating element used in household appliances.
For continuity, the current inside the resistor will be the same as the current on the wires connected
to its terminals, let us call it .
Figure 1.4-1 A Simple Resistor
Through equation (1.3-1) we can relate the current thought the resistor to the magnetic field inside
it.
Also, since the electric field inside the resistor may be considered uniform, it is easy to relate the
voltage across it to the respective electric field through equation (1.2-1)
∫
∫
(1.4-1)
(1.4-2)
(1.4-3)
High resistance wire
Leads
Conquer Radio Frequency
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