LinkBack Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
  #7   Report Post  
Old July 7th 10, 01:05 PM posted to rec.radio.amateur.antenna
joe joe is offline
external usenet poster
 
First recorded activity by RadioBanter: Feb 2010
Posts: 55
Default what happens to reflected energy ?

Keith Dysart wrote:
current law derives from conservation of charge.

Still, you have made some progress, so I will try again with showing
the derivation, though this time with charge and current.

Conservation of charge requires that:
the charge added to a region
- the charge removed from a region
equals
the charge originally in the region
+ the increase of charge stored in the region

When the charge can be described with functions of time, we can write:

Qin(t) - Qout(t) = Qoriginal + Qstored(t)

Differentiating we obtain

Qin(t)/dt - Qout(t)/dt = 0 + Qstored(t)/dt

At a junction, where charge can not be stored, this reduces to

Qin(t)/dt - Qout(t)/dt = 0

Alternatively

Qin(t)/dt = Qout(t)/dt

Recognizing that Q(t)/dt is charge flow per unit time or current
we obtain Kirchoff's current law, colloquially: the current flowing
in to a junction equals the current flowing out of a junction.

I leave it to you to do the similar derivation for energy, based
on conservation of energy. The result will be

EnergyIn(t)/dt = EnergyOut(t)/dt

And similar to Kirchoff, this applies at a juncion, a place where
energy can not be stored.

Of course Energy(t)/dt is just a mathematical expression of energy
flow or power, so we obtain

PowerIn(t) = PowerOut(t) (at a junction)

But don't beleive me. Do the derivation yourself. You can pattern
your derivation on the one above for Kirchoff.

I'd go on to show how my analysis of your circuit carefully
picked junctions that could not store energy, but I have found
it better to educate one step at a time. So we can do that
later.

...Keith



How do you define energy of a node without reference to another node.
How is it measured?

 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
what happens to reflected energy ? JC[_3_] Antenna 317 July 10th 10 05:51 PM
what happens to reflected energy ? Keith Dysart[_2_] Antenna 0 July 6th 10 06:20 AM
Reflected Energy Cecil Moore Antenna 12 November 19th 04 09:01 PM


All times are GMT +1. The time now is 03:21 PM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017