WolframAlpha guide on electrical engineering

[waht]

Introduction:

WolframAlpha is a freely available computational engine that can supplement already existing software such as mathematica, maple, mathlab, or excel. The purpose of this mini-guide is to go over some of its functionality with emphasis on electrical engineering.

www.wolframalpha.com


Dimensional analysis:

WolframAlpha recognizes many common units. It will simplify dimensions and scale units. For example,

farad * henry

will generate [time]^2

0.01 uF to pF

will generate 10,000 pF or 10 nF


WolframAlpha also can tap its database to pull up a conversion formula from the context

convert 25 MHz to meters

will convert the frequency to wavelength 12 meters

find energy in 100 uF at 10 KV

will give energy in a capacitor,

or to find inductance to resonate with 10 nF capacitor at 100 Khz; just say that

find inductance for 10 nF at 100 KHz

output 253 nH

Also if you haven't memorized resistor color bands already, you can still look them up

resistor yellow purple red

output: 4.7K


Complex numbers and phasors:

Working in polar form is supported in W|A. By typing an impedance in rectangular form

30 + 45i

we are quickly given its magnitude and phase of 54, and 56 degrees

and likewise, we can indicate a phasor in polar form with an exponential e

e^(i pi)

generates -1

we can also manipulate phasors algebraically

100 e^(i 45 deg) + 25 e^(i 30 deg)

output: magnitude = 124, phase = 42 deg

indicate degrees with “deg” otherwise W|A will interpret it in radians.


Solving equations:

To solve $x^2 - 2x + 1= 0$, enter the equation as it is

x^2 - 2x + 1 = 0

output x = 1

and W|A solves it. Don't even have to specify the variable to be solved.

Solving systems of equations is just as easy,

$$v_1 + v_2 + v_3 = 4$$

$$v_1 - v_2 = 10$$

$$v_1 - 3v_2 + 5v_3 = 8$$

simply type

v1 + v2 + v3 = 4, v1-v2 = 10, v1 - 3v2 + 5v3 = 8

output v1 = 23/3, v2 = -7/3, v3 = -4/3

just make sure that the equations are separated by a comma.

Differential equations are supported as well. An nth number of apostrophes indicates an nth derivative, and proceed as before. For example to solve

$$\frac{d^2y}{dx^2} - \frac{dy}{dx} - 2y = 0 \indent y(0) = 1, y'(0) = 2$$

enter the code as follows,

y'' – y' - 2 y = 0, y(0) = 1, y'(0) = 2

and we get a solution y = e^2x as well as a plot that can be saved in pdf format, and printed out.


We can also maximize and minimize

max 1 - x^2

finds maximum of 1


Logic gates and boolean algebra:

Converts number bases,

binary 1111101 to hex

= 7d


We can also work with boolean expression in WolramAlpha, for example

(x or y) and (x or !y)

generates a truth table:


http://img200.imageshack.us/img200/9384/truthtable.gif [Broken]

a schematic with logic gates, and even simplifies the expression to a minimal form

http://img268.imageshack.us/img268/3233/scehmatic.gif [Broken]

Here is the supported syntax:

NOT = !
OR = ||
AND = &&

NAND
NOR
XOR

More on calculus:

W|A can perform basic calculus

take derivatives:

$$\frac{d}{dt} cos(t)$$

derivative cos(t)

do integration:


$$\int \frac{1}{x+1} dx$$

integrate 1/(x+1) dx

and take Laplace and Fourier transforms:

$$\mathcal{L}(x^2), \mathcal{F}(e^x)$$

laplace x^2

fourier  e^x

Plotting:

If you want to graph a transfer function for instance,

$$H(s) = \frac{s+10}{s^2 + 4s + 8}$$

enter:

 graph (s + 10)/(s^2 + 4s + 8)

and here we have

http://img32.imageshack.us/img32/9715/graph.gif [Broken]


Conclusion:

WolframAlpha uniquely combines different tools into a one freely available package and that expands our tool box. This mini-guide doesn't cover all of W|A, it merely touches upon features that can be used in electrical engineering, for more information visit their examples page

http://www28.wolframalpha.com/examples/

also, W|A is said to expand in the future, enabling more functionality, and tools.

 

[berkeman]

Thanks for putting that together, waht. I've stickied this thread to help us learn how to utilize W|A.

Any further posts in this thread should be about tips on how to use W|A and its features. Discussions about W|A and its implications for eductaion, etc., belong in a different thread, like this one: https://www.physicsforums.com/showthread.php?t=307686

.

 

[Redbelly98]

Resistor color codes

Also if you haven't memorized resistor color bands already, you can still look them up

resistor yellow purple red

output: 4.7K

The inverse operation works also. Type this for input:

resistor color 4.7k ohms

... and the output is an image of the resistor with the correct color bands:

View the full W|A output here:
http://www5f.wolframalpha.com/input/?i=resistor+color+4.7k+ohms&asynchronous=false&equal=Submit [Broken]
.
.

 

[Redbelly98]

WolframAlpha calculates parallel resistor combinations:

http://www.wolframalpha.com/input/?i=solve+1/R+=+1/1200+++1/4700

 

[dvchench]

WHOA!
http://www.wolframalpha.com/input/?i=low+pass+filter designs filters for you

http://www.wolframalpha.com/input/?i=op+amp

also, a simpler calculator for the parallel resistances,
http://www.wolframalpha.com/input/?...ms&f3=20+ohms&f=ResistanceParallel.R2_20+ohms

also, very nice inductance calculations for the RF geeks:
http://www.wolframalpha.com/input/?i=inductance+of+coil

 

[ranger]

Check out the WolframAlpha app for the iPhone and iPod Touch. Its pretty awesome!

 

[rathat]

Remember when the WA app cost $50? They thought because it's better than any scientific calculator could be, they could charge that much, but you know, no one would pay that much so they made it $2.

 

[Ecin]

is there any advantage over the ipod app vs the standard web version?

 

[CenterFusion]

Would you guys recommend wolfram alpha to a student who is interested in learning more about physics and modeling physics within computing systems? I have a small bit of experience with mathlab, and am hoping to be on the go as I do this (iPad, Android, etc.)

 

[m.s.j]

I have "Algeo.apk" in my galaxy tab, it is a wonderful application in small scale.