Math / Science

The Math / Science topic primarily includes discussions of mathematics, physics, statistics and economic analysis, but also biology, chemistry and other sciences.

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I'd like to use Photoshop to be able to construct Floor Plans for home building.

In my initial research I noticed the Measurement Scale option that is an inches to pixels conversion. This seems to work well, but isn't quite accomplishing what I want:

I'd like to set this up for Inches to Feet, such that 1/4" is equal to 1' for the sake of accuracy. So, a quarter-inch on the screen (presumably Greyscale at 300dpi) is equal to a foot in real life.

I appreciate your assistance as it turns out that yes, I do indeed need to do math for this.

Bootstrap 4: Exploring New Features
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Bootstrap 4: Exploring New Features

Learn how to use and navigate the new features included in Bootstrap 4, the most popular HTML, CSS, and JavaScript framework for developing responsive, mobile-first websites.

The Point is      x=0.6160      y=0.8308
Determine coefficients of the equation for a second order polynomial in the format:
I want to know how does the body processes oils that we eat.
Does the oil gets stored in the body ?
Or does it get expelled.
Is there any good video explaining it ?
And good site or anything which shows the link between food and its processing and how good food effects the body and how bad food destroys it.
What makes junk food bad why does it cause diseases etc etc ?

STEM education is growing rapidly and preparing the next generation to fulfill the needs of our society's technology demands.  

In what ways has EE helped you continually learn, even as professionals?
How can EE support STEM as a great learning resource?
I have an image which is 320x240 px

I have an array of values for each pixel in the image (76,800 points)

If the user hovers over any part of the image I need to look at the array and return the corresponding value for it.

X Y position [0,0] of the image = the first value in the array.

If I wanted to find out the X Y position [65,33] of the image, and then look up the  value in the array, what would be the correct forumla to do this
I was thinking about magnetism and it seems that both immobile charges are affected.

We have a wire conducting current and we have a positive charged cat.

At our rest frame the cat won't be repulsed from the wire . But in another frame when we consider the electrons (which are the current) immobile then due to length contraction the charge density of both the cat and the nuclei will be increased so a repulsive force will exist.
In forward bias mode there is an energy difference between electrons from n-type doping  and electrons moving from the semiconductor material  because of the difference  band gap .

Where does the remaining energy go?
Well I was revising how 'magnetic' force is created and I came up to an issue?

Why do we measure only the charge net density only from a frame reference that electrons dont move?
I recently drove my car into the outside of my house and the circa 1860 plaster fell off the inside wall due to the impact.

The house is still structurally sound but the plaster that fell off the inside wall really smells bad. What is creating that horrible smell and how can I get rid of it?
We have a reference system in a conducting coil . Our reference velocity is the velocity of current(electrons).

Why the spacing between the nuclei is smaller than if we take as reference system with reference velocity the velocity of nuclei?

Length contraction decreases the dimensions of the nuclei , not making smaller the spacing between the nuclei.
Why Diversity in Tech Matters
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Why Diversity in Tech Matters

Kesha Williams, certified professional and software developer, explores the imbalance of diversity in the world of technology -- especially when it comes to hiring women. She showcases ways she's making a difference through the Colors of STEM program.

Are LED's forward voltage dependent on the type of the semiconductor?

For example if a Led emmits red light is its forward different from a LED that emmits blue light?
Well an LED's colour is determined by the energy band of  the semiconductor(GaAs). If the impurities have different  energy band than the semiconductor  where does the remaining energy go?
I would like to ask how current flows through a water doped with NaCl

*First H20 molecules dissolve NaCl. Na+ and Cl- are created .

*When we apply a external voltage source Cl- anions are attracted to the positive electrode(cathode) and Na+ cations to the negative electrode(anode)

*2 Cl- anions are oxidized according to this reaction 2Cl- ->Cl2 + 2e-

*Those 2e- travel through the battery and go the cathode where they meet 2Na+ + 2e- +2H20 -> 2Na + 2OH- +H2

how does current flow after this?

Is current carried with OH- . If yes how and why?
Well i would like to ask this :

If a transistors is on active mode

Diffusion current flows from the emmiter towards the base.

Some electrons combine with holes in the base and then spread towards VB voltage

Most of electrons have no holes to combine so they create the output current

How is it possible those electrons(which are very many)pass as an drift current (Base-Collector junction reverse biased) only as minority charge? I mean there are not enough free electrons in the p-type region(base) to allow all of those electrons to pass
Well i have a question:

Here it is my circuit

The circle with the arrow is an npn transistor

why when i increase the value of R1 and voltage drop  in R2 gets bigger?

well im having this trouble for several days.

where am i wrongThe circle with the arrow is an npn transistor
Hello and Good Morning Everyone,

           I am wondering why C14 (subscript) would be used in a disinfectant/virucide.  I always thought that it a radioactive substance used in carbon dating of very old materials by archeologists and nothing else.   If used in a day to day disinfectant/virucide, could it be considered potentially carcinogenic to humans?

           Any feedback given to this question will be appreciated.

           Thank you

Why when I increase the  base resistor  the VCE voltage drop dicreases?
I have a circuit with a transistor and a light emmiting diode:

My source voltage is 11.6 volts

My transistor is in series with 2 resistors and the light emmiting diode.

The resistors values are 1000 Ohm each.

The base is connected to a 0.7 volt supply.

Voltage drop in resistors is 2.7 volts each.

The voltage drop in the light emmiting diode is 2.7 volts

Why is there a 3.4 V voltage drop between emmiter and collector?Shouldnt it be 0 and the voltage drop in the resistors be (11.6-2.7)/2 volts ?

What am i missing?
Hello and Good Evening Everyone,

        From a label on a disinfectant viricide bottle, I noticed an area listed as Inert Ingredients with a percentage of 99.93%.  Didecyl dimethyl ammonium chloride being  .04% and dimethyl benzyl ammonium chloride being  .03%.  Given this information, I am wondering what is meant by Inert Ingredients.  

         Any clarification which can be given for the meaning of Inert Ingredients will be greatly appreciated.  

         Thank you

Exploring SQL Server 2016: Fundamentals
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Exploring SQL Server 2016: Fundamentals

Learn the fundamentals of Microsoft SQL Server, a relational database management system that stores and retrieves data when requested by other software applications.


Need help with a formulas to calculate:
1. (Cell DM23) Most recent past 6-week run rate of 52 week historical data that excludes zeros and high- low numbers (seasonality/Standard Deviation > X).
2.  (Cell DN24) Return data in Range $BM$22:$DL$3171 in column DN depending on current week written in Cell DM16

(see attached file)
Well i would like some help here:

A semiconductor's resistance is relevant to its impurities . The p-type doped region in an NPN transistor is very thin.So Why many electrons pass through from the emmiter to the base since base resistance is very big?
I need to learn embedded software and hardware development life cycle and use it to create electronic hardware/software component.  I need to approach this job systematically.  For example, what is the order of tasks.  Probably requirements should be gathered and documented.  Then, what's next and so on?  At what stage should we select hardware components.
Attached is Matlab command to convert polar form to rectangular form.  I'm converting 2e^j(pi/2) to rectangular form.

I was expecting real part to be 0 but it's a very small number.  Is this because there isn't enough bits to represent 0?
Nonstop train leaves Toronto and Montreal at the same time each day going to the other city along the main line. One trai travels at 120km/h and the other at 90km/h. Assuming the train is straight, how apart are they one hour before they meet?

The distance between Toronto ans Sudbury is 418 km. Terry leaves Sudbury on his motorcycle and went 105 km towards Toronto. Damon left Toronto at the same time on his motorcycle and drove 215 km towards Sudbury. How apart are Terry and Damon ?

Be a power thinker and solve this number puzzle by finding the correct values for A and B. The pictures are important

      A - B = 2                                  A(A in square) + 2 = B(B in cube)
For a number sequence A: (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

Are the terms in the subset B: (1, 4, 7, 8) considered in sequence given that some numbers from A were skipped?

Should I use the adjective sequential or succedent, or is there a better word?