# max power transfer theorem

Discussion in 'Homework Help' started by haditya, Nov 19, 2004.

Jan 19, 2004
220
0
the other day we were conductiin expt for verification of max power transfer theorem.
we ogt the results more or less accurately but i hav a few doubts...
max power is said 2 be transfered from source to load if Ri=RL
at this condition efiiciency is 50%
on increasing Rl greater than Ri...we found that efficiency increases :blink: :blink:
theoriticall it becomes 100% for Ri=0...which is practically impossible..
my question is how can efiiciency be greater then 50%...if max power is transfered at 50% efficiency :blink:

2. ### pebe AAC Fanatic!

Oct 11, 2004
628
3
It's more accurate to say that maximum energy is transferred when the *output* resistance Ro=RL, because the power source has an output resistance, and the load has an input resistance.

When Ro=0, it's the same as wiring a lamp direct to the mains supply, and all available power can be taken by the lamp.

But the max power Ro=RL concept is applicable when you are faced with a power source that has a finite Ro, and it is necessary to match the load so that it can take maximum power.