Power of Ideal Voltage Sources: Is it Infinite?

[alphaomega@ho]

hello,

in my course I read about ideal sources
- an ideal voltage source holds a constant voltage , no matter the currect it's giving
so can I conclude that those types of sources has an infinite power in itself ?
(power = voltage x current)
maybay a stupid question...

thank you

 

[dlgoff]

Yes, for voltage sources. The reason being that there is no internal resistance of the source. If there were, the voltage would sag (decrease) due to sourcing currents.

Welcome to PF

 

[sophiecentaur]

It's like an irresistible force or an immovable object. Just a concept.

 

[alphaomega@ho]

thank you for your replies !
i am studing engineer and want to fully understand everthing

 

[sophiecentaur]

I might point out that the concepts of current and voltage sources are very useful because of the actual values of quantities you deal with in most practical electrical problems.
To get 'near enough' to a voltage source, all you need is the source resistance to be a small fraction of the resistance of the load and then you can 'ignore' source resistance in your calculations.
A 'reasonable size' fully charged battery can usually be treated as a voltage source when connected to a 'typical' small electronic circuit.
The collector of a transistor can very often be treated as a current source when the collector load has a value of even 100kΩ.

Using feedback in circuits involving amplifiers makes the effectiveness of a voltage or current source even better because the circuit does its damndest to maintain the volts or current it 'wants'. But the constancy will only hold over a limited range of values - after which the amplifier may run out of steam.

 

[alphaomega@ho]

thank you for the replies,

I think I understand it now
do you have also a couple of good examples/excersis about law of Kirchhoff/supersposition/star-delta transformation/thevenin - norton equivalence

thank a lot !

 

[gnurf]

do you have also a couple of good examples/excersis about law of Kirchhoff/supersposition/star-delta transformation/thevenin - norton equivalence

Do you have a couple of good questions about any of those?

 

[alphaomega@ho]

not exactly, I understand the priciples
but inmy course there aren't a lot of excersises so...

thank anyway

 

[dlgoff]

do you have also a couple of good examples/excersis about law of Kirchhoff/supersposition/star-delta transformation/thevenin - norton equivalence

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/norton.html#c1"
http://hyperphysics.phy-astr.gsu.edu/HBASE/electric/nort2l.html#c1"
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/thevenin.html"
http://hyperphysics.phy-astr.gsu.edu/HBASE/electric/thev2l.html#c1"