1. ### I Accuracy of the Density of States

I'm trying to understand the detailed concept of why the density of states formula is accurate enough to calculate the number of quantum states of an energy level, including degeneracy, within a small energy interval of ##dE##. The discrete energie levels are calculated by E = \frac{h^2 \cdot...
2. ### Biology Micropipetting

Used a P100 to pipette 93.6 micro-litres of fluid. There was an air gap in the pipette tip the first time I did it but no air gap the second time. I'm assuming there shouldn't be an air gap but can somebody tell me for sure?
3. ### Determine acclimation time for metals

A little background: Inspection room is kept at 20 C +/-2 C. Temperature gauge is accurate to +/-.5 C. Outside ambient temperature where parts are kept can vary from 5 C to 38 C. One part in particular is a rotor made of 4340 steel, ~2350mm long, average diameter of 115mm, and weighs ~ 650lbs...
4. ### Use math to prove which lab equipment was precise/accurate?

Homework Statement We performed an experiment to see which laboratory glassware was more accurate and which was more precise. Question: (a): Which glassware was more precise and why? (b) Which glassware was more accurate and why? Use the calculations to support your statement. I won't post the...
5. ### I Error in declination of linear regression

During a lab exercise we measured different masses of a magnetic material on a scale while changing the strength of the magnetic field it was in. Afterwards we plotted the masses and the fieldstrength hoping to find a linear slope. Then we drew a linear slope by using linear regression and found...
6. ### I How to write measured value with error

During a labexercise we measured a value to be 26.3 mT. The teslameter was said to have an accuracy at +- 0.05%. This means we measured 26.3 +- 0.0132mT. However we are supposed to write a measured value with it's error in the last digit. But the error is smaller than the smallest digit we got...
7. ### Power supply for multiple devices -- effects on accuracy

Hi, For my project I am plotting a Force vs Displacement graph using 2 analog inputs which are going to a DAQ. The two analog inputs are coming from; -A 5k potentiometer (for the displacement) -A 1000 lb load cell sensor (for the force) I would like to use a regulated 12V DC (1Amp) power...
8. ### Maximum Theoretical Angular Accuracy of Planer arrays

Hello, in this link http://dtic.mil/dtic/tr/fulltext/u2/a028054.pdf a paper „Maximum Theoretical Angular Accuracy of Planer and Linear Arrays of Sensors“ can be found. The accuracies are given in equations 19 (respect to the x axis) and 20 (respect to the y axis). My question is: Shall the...
9. ### Rutherford Backscattering Spectroscopy, Counting Statistics

Homework Statement I am given a numerical example (to be solved with pen, paper and calculator only) of an RBS spectrum of a AuAgCu-alloy on a glass-substrate. The question is "Can you get the composition? How accurate is the result? Homework Equations All the Rutherford Backscattering...
10. ### Experimental Error in Archimedes Principle Lab

Homework Statement I need to find three potential reasons for my .5% error in a lab where I used the Archimedes Principle to measure the density of Iron. We only used a graduated cylinder full of water and an iron mass. I measured the water level from the meniscus. We used two different...
11. ### Heat equation order of accuracy (Crank-Nicolson)

Hi, Let's consider the heat equation as \frac{\partial T}{\partial t}=\alpha \frac{{{\partial }^{2}}T}{\partial {{x}^{2}}} In order to have a second accuracy system, one can use the Crank-Nicolson method as \frac{{{\partial }^{2}}T}{\partial {{x}^{2}}}\approx \frac{1}{2}\left(...
12. ### Definition of Accuracy

Hey, i am trying to teach accuracy and precision. I understand precision to mean two things. How repeatable measurements are (variation), and how specific measurements are (sensitivity). I am having a bigger problem defining accuracy. Most places i look define accuracy as how close...
13. ### Accuracy of an Optical Spectrum Analyzer (OSA)

Hey! I've a simple (and maybe stupid) question about the accuracy of an OSA. The datasheet report a level accuracy of 0.4 dB but this seems quite strange to me. Indeed level measurements are done in dBm thus, as long as dB measures a relative power, I assume that even the 0.4 dB are referred to...
14. ### Observational error and FWHM

Hello, i have a optical signal(x is length in pixels and y is amplitude ) and i have found a number of FWHM values of peaks. The width is measured in pixels, let's say the average width of 50 peaks is 8,7 pixels, standard deviation is 0,6 and the average amplitude of peaks is 38 and standard...
15. ### Can we accurately measure the momentum of a particle?

Is there any law that prevents us from accurately measuring the momentum of a particle , just like the energy time uncertainty principle makes us observe the system for an infinite amount of time before we can be certain about its energy? I got this doubt because if we can do it, we will...
16. ### Tennis Ball Launcher

Hey all, I need to build a launcher that is capable of throwing a tennis ball over a 1 meter high wall and hit a target 2 meters away. I realize there are some threads already discussing this, but my question is more based on the type of launcher. Would a trebuchet or a spring powered cannon be...