Recent content by Mr. Johnson

Ok. Thank you.

I have...It says nothing about measuring the EQE.

Hello PF, I am currently studying OLEDs (organic light emitting diodes) and have been reading many articles pertaining to the external quantum efficiency of these devices and the various extraction techniques used. In all of these articles, they state the increase of efficiency but do not...

Ok so I found an example but I feel like it isn't very intuitive and that there are better methods and approaches to this problem. So here is what I did: The hyperplane W is of the form Ax1 + Bx2 + Cx3 + Dx4 = 0 since it must pass through the origin. rref ( 3 1 -2 -1) =...

Let W be a hyperplane in R4 spanned by the column vectors v1 , v2, and v3, where Note that these are suppose to be COLUMN vectors: v1 = [3,1, -2 , -1], v2 = [0, -1, 0 , 1], v3= [1,2 ,6, -2] Find the Cartesian (i.e., linear) equation for W. I'm not quite sure where to start or how to...

Thank you khemist.

Homework Statement [PLAIN]http://img14.imageshack.us/img14/4355/screenshot20110807at249.png Homework Equations v(t) = Vmax * e^(-Rt/L) i(t) = imax * e^(-Rt/L) P = V^2/R w = integral of power w/ respect to time w(0) = .5Li^2(0) = energy stored in inductor The Attempt at a...

Hello, I am currently studying RL circuits and I know that when an inductor is attached to a resistor of large value, the time for the energy stored in the inductor to dissipate in the resistor is shorter and vice versa. This is proven mathematically by the time constant term Tau : L/R But...

weight (force) = mass times gravity mass = weight (force) divided by gravity Her weight is 700N and gravity is 9.81m/s^2

It's ok. I guess we were over thinking it a little... But thank you for your help. It is much appreciated.

I still don't understand why it wouldn't work to just use the same circuit as before with the same settings (two DMMs connected, one on measuring current, the other measuring resistance). The reading on the resistance measuring DMM wouldn't be the value of the shunt resistor of the other?

So I asked the instructor if the two circuits were correct and he said that for the first one, we don't need to hook any DMM to a resistor. So I guess just hook both the DMMs together with one measuring resistance and the other measuring current? He said the second part wasn't quite right...

By just connecting the DVM in parallel w/ resistance measuring mode. So I should just measure the shunt resistor by connecting the two prongs of both DVMs together (one of them turned off and the other to resistance measuring mode)? Isn't there any other conducting material in the DVM that...

You would have to either know the current going through that resistor or voltage across the two resistors in parallel ( assuming that you know the value of the higher resistor) and use voltage division. I'm not quite sure...

Or put it in parallel ( in voltmeter mode) with the ext resistor and divide the measured voltage by resistance. I'm still having trouble with the second question...use voltage division ?