# The Naked Scientists Forum

#### rachel2005

• First timers
• Posts: 2
« on: 09/04/2006 18:10:31 »

Can someone teach me how to find power delivered to the 15Ù resistor?

If I replace the 15Ù resistor is replaced by a variable resistor, what is the value of the variable resistor value that will yield maximum average power transfer to RL?
Then what is the maximum average power transferred to RL?

Can anyone help me out? I really have problems for working into this circuit. Thanks.

#### rachel2005

• First timers
• Posts: 2
##### Re: Questions about a circuit..
« Reply #1 on: 09/04/2006 18:13:37 »
Hi, just wanna make it clear that the 15Ù is actually 15 Ohms.

#### another_someone

• Guest
##### Re: Questions about a circuit..
« Reply #2 on: 09/04/2006 22:45:13 »
It's a good many decades since I last did this kind of thing in anger, and I've been trying to find the actual equations that will back up my instinctive response, but have not yet found it.

Since, as far as I can see, both sides of your transformer are equal (i.e. same number of turns, same field strength), thus there will not be any adjustment in impedance from one side of the circuit to the other, so I would expect peek power to be when the impedance on both sides match (i.e. both sides with 5 ohms impedance).

As I say, I have not yet been able to find the equations that will back that up – but then, I can't see how it could be anything else, since there is no step-up or step-down through the transformer.

George

#### curtinstudent

• First timers
• Posts: 1
##### Re: Questions about a circuit..
« Reply #3 on: 01/05/2006 09:51:51 »
OHHH MAAAAAAAAA
I'm Dobbing :P

#### The Naked Scientists Forum

##### Re: Questions about a circuit..
« Reply #3 on: 01/05/2006 09:51:51 »