The Rest of the Story
On Apr 16, 10:04*am, Cecil Moore wrote:
Keith Dysart wrote:
Q1. Where does this [source] energy come from?
An ideal source simply supplies a fixed voltage
devoid of any concern for efficiency or where
the energy comes from. This results in an
average steady-state number of joules being
supplied to the closed system per second.
Q2. Where does this [reverse] energy go?
You have morphed the questions. Let us try again.
Try two ideal voltage sources arranged in the
circuit below.
5 ohms
+----------\/\/\/\/-----------+
+| +|
Vsl=10 VDC Vsr=5 VDC
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+-----------------------------+
Using the circuit analysis technique of your
choice you should find that 1 amp is flowing
through the resistor.
The ideal voltage source on the left is providing
10 joules/second to the circuit.
Q1. Where does this energy come from?
The ideal voltage source on the right is absorbing
5 joules/second from the circuit.
Q2. Where does this energy go?
Answer to both. We do not know and we do not care. An
ideal voltage source can deliver energy to a circuit
and it can remove energy from a circuit; that is part
of the definition of an ideal voltage source. It does
not matter how it does it.
But just as easily as it can supply energy, it can
remove it.
Without understanding these basics of the ideal voltage
source, it will be impossible to correctly analyze
circuits that include them.
This has been the root cause of the misunderstandings.
...Keith
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