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VK6JY > TECH 17.10.06 13:28l 65 Lines 1026 Bytes #999 (0) @ WW
BID : 22759-VK6JY
Read: GUEST DL1LCA DL8FBH
Subj: Re: physics problem
Path: DB0FHN<DB0MRW<DK0WUE<CE8FGC<VK6HGR<VK6TJ<VK6JY
Sent: 061016/1620Z @:VK6JY.#ALY.#WA.AUS.OC #:22759 [Albany] wFBB7 $:22759-VK6J
From: VK6JY@VK6JY.#ALY.#WA.AUS.OC
To : TECH@WW
>From: DK2ZA @ DB0FOR.#BAY.DEU.EU (Helmut)
>To: TECH @ WW
>
> Here is one problem from a german physics contest for 16 year olds:
>
> You have three resistors R1 = 10 Ohm, R2 = 20 Ohm and R3 = 30 Ohm.
>
> Each resistor can absorb at most 5 Watts. You have only one source
> of electrical power, the voltage of which can be adjusted to any
> necessary value.
>
> How do the resistors have to be connected so that when voltage is
> applied the total absorbed power is a maximum?
> How many watts will that be?
>
> Have fun and vy 73 de Helmut, DK2ZA
VK6JY says max power is 10 watts.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:<--V source-->: Max power when V = (R3xP3)^0.5 = (30x5)^0.5 = 12.25
: :
:--[R1]--[R2]--: P1 = 1.666W P2 = 3.333W P3 = 5W
: :
:-----[R3]-----: P(total) = 10 watts (removing approximations)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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