In this lab, we couldn't make a short circuit so we were instructed to measure the Vout for different load resistances (20ohm,30ohm,50ohm, etc) How does that help me find Rth. From those two values, I'm supposed to calculate Rth for each.
oh and Vth = sin(2*pi*1000t)
the only other equation i have is from using a voltage divider on the circuit and getting Vout = Vth(Rload/Rload+Rth)
2007-10-29 04:47:47 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Engineering
You actually have more data points than just the voltage across the load for 20,30, and 50 Ohms. You also have the data points of all 3 in parallel (9.67 Ohms), 20 and 30 in parallel, 20 and 50 in parallel, and 30 and 50 in parallel. Then you have 70, 80, and 100 Ohms (using resistors in series).
Measure the Vout and plot it against all 10 load resistances. More importantly calculate and plot the Power into the load versus the load resistance (for all 10 of them).
If the Thevenin resistance of the source is anywhere in the range of 9.67 to 100 Ohms you will see a peak in the power curve at the internal resistance of the source (because maximum power is transferrred when the load resistance is equal to the Thevenin resistance).
If the Power does not peak anywhere in that range (9.67 to 100 Ohms) but keeps rising as the resistance gets lower, then the internal resistance of the source is lower than 9.67 Ohms (and it may be something like a battery, but putting out 1000Hz AC).
I suspect you will probably see a peak at 50 Ohms, if this is a 'standard' signal generator.
.
2007-10-29 05:20:02 · answer #1 · answered by tlbs101 7 · 0⤊ 0⤋
Find the current by dividing the closed circuit voltage by the 20 ohm load resistor. Then divide the open circuit voltage by the current to find the toal resistance. Then subtract the 20 ohm load resistance from the total resistance. The remainder is the thevevenin resistance.
2016-05-26 00:21:10 · answer #2 · answered by ? 3 · 0⤊ 0⤋