iwfc87

Hey all,

Just a question on this

How efficient are commercial wind turbines in producing electrical energy?

By the the term commerical wind turbines, I mean the ones they use in Wind farms.

Thanks.

whoa..that didn't come out as i expected.

but the 1st column is Resistance

2nd is voltage and 3rd is current in mA

yeah i know..

I was getting the results off the digital multimeter, and it was weird.

Though there could of been various errors that caused this, such as the resistor's tolerance of 5% or the sunlight's intensity and colour not being constant causing the results to be different.

R= (Ohm) all ±5% V= v Current=mA

12 0.76 63.9

33 2.11 64.3

100 6.22 63.3

220 12.95 59.8

470 16.06 32.2

1000 16.82 17.1

So yeah..I got the voltage and current readings off the multimeter. I don't know whether I should use the multimeter's reading or my calculated reading, but I have a feeling I should use the multimeter's.

Thanks.

So the current can be different values?

So if my current is 0.063A (it's one of my values when a 12 ohm resistor is used), my terminal voltage would be

VT=23.547 - 287.59 * 0.063

VT=5.43 V

I think I understand it now!

Thanks a lot for all your help!

So if my line drawn has the equation of y=-287.59+23.547x, what does that mean?? *confused*

Thanks.

Oh..my values were 23.54 when crossing the Voltage axis, and 0.0817 when crossing the Current axis.

Hence using the formula as advised, my Rinternal= 288.13 (this is pretty large if u asked me)

Now if I use VT=EMF-I*r,

VT= 23.54- (0.0817 * 288.13)

VT= -2.21 EXP-4

Would this be right? It doesn't seem so to me, but it could be :S.

Thanks a lot

(Sorry for bugging you guys so much. I enjoy physics, just takes me a while to understand it!:S)

Sorry for being so unclear in writing formulas etc.:S. I'm pretty much a newbie

I think I've solved the error now. I just got confused with the formula because the information sheet I got made it look confusing! WHoops >_<.

THanks a whole lot for everyone's help but!

Your all legends!

Hey, I'm back again.

I've done as Kedas recommended in his reply to my 2nd question, and some how my calculated internal resistance is very high.

If I then tried to apply this internal resistance to V t= EMF-Ir, where Vt is terminal voltage and Ir is internal resistance, I get a negative terminal voltage because my Ir is very large.

I've taken the EMF as the voltage intercept of the graph.

Thanks.

Lol..yes and no.

I've been trying to think about it but I can't seem to figure it out, and sometimes I don't understand the question/s.

Sorry bout that!

But thanks a heap though. Makes things a lot easier to understand!

Hi, I'm doing an experimental write up report based on an experiment I did at school and the title is Voltage-Current Characteristics of a Solar Cell.

What we did was to use different resistors of different resistors and put in a circuit powered by a Solar cell and then record the voltage and current of the circuit.

What I need to know is:

1. What is the power delivered to the resistor and how can that be calculated?

2. How would you calculate the internal resistance if I graphed it out?

3. If i drew a graph of power delvired to the resistor (y-axis) and Resistance (x-axis), how would I estimate the resistance for which the power is delivered is the maximum?

Thanks a lot.

Hey, how's it going?

Ok..I've got this question that's popped out in this physics test and I don't know if it belongs in this category of the physics section of the forum. I've been getting mixed responses to this question and I just wanted to know what you all though. Here goes:

A heater is connected to 240V AC and is made up of 2 identical heating elements, with the same resistances. The heater has a switch that allows the heater to be swtiched on to a High Setting, a Medium Setting or Low Setting. This switch causes the 2 heating elements to be connected to the circuit differently.

Parallel, Series and only one element is heated.

Which circuit would be best for the high setting, which circuit eould be best for medium setting and which circuit would be best for low setting. Justify your answer.

There it was.

Thanks!