Imagine...

You are just about to do the "Photoelectric effect" lab in your college junior physics class. Your teacher has been telling you that when you shine light on metals, electrons just fly out of them. Furthermore, she insists that the speed at which electrons fly out does not depend on the intensity but on the color (wavelength) of the incident light.

First you get familiar with the experimental setup. You will measure the electric potential needed to stop the electrons from flying out of the metal. This potential is related to the energy that electrons have and therefore to the speed at which they are flying out of the metal. Great, you think, now I can check this funny photoelectric effect for myself.

You pull out your handheld PC.

You start up the freehand drawing and note taking software, on your handheld and sketch the apparatus using the stylus pen directly on the touch-sensitive screen. You will use it later in your laboratory report.

Next, you bring your handheld PC to your teacher's desk. Using an infrared communication port, she transfers needed equations and constants for this experiment from her computer to your handheld. Now you are ready to begin.

You open up your pocket spreadsheet software and prepare to enter your data and observations directly into it.

First you use white light (from a Mercury lamp) and you record the stopping potential for various light intensities. You immediately plot the data on your handheld PC using a data graphing software. WOW ... measured potential is constant within the experimental error. So, the teacher was right!

For the second part of the experiment, you shine different color light (from the mercury lamp whose light you pass through a diffraction grating - to separate white light into its constituent colors) and you record the stopping potential. Now you would like to plot the wavelength of the light (color) versus the stopping potential. But wait - you don't know the exact wavelength for the colors you used.

You decide to look at the information file that your teacher beamed to your handheld via the infrared port, and surely enough the color-wavelength chart is included there.

You again use your graphing program to plot the data. You are stunned! It looks like the speed of those electrons does indeed depend on the color of light. You look at the provided equations and realize that by calculating the slope of the line in your plot you can determine Planck's constant. Incredible. So you do it right there on your handheld PC, slope determination and all. What now? Well, lets check if the result for this constant is right. Surely you can find the actual value for Planck's constant on the information sheet from your teacher. You look and look but it is not there. Damn! What now?

You regain your cool in a moment and hook up your handheld's 56K built-in modem to the phone jack at your lab station and log on to the PhysLINK.com web site. A click to their reference page and you get the 'official' value of Planck's constant. Good news! Your measured value agrees with the actual value within experimental error. Great! This lab was a success. You learned a lot and your are confident in your results. Writing a lab report will be a snap.

Finally, your teacher tells the class that the person who discovered the photoelectric effect actually got the Nobel Prize for it and some other theoretical work. She continues, "And who ever figures out the name of this scientist will get extra points". Now the race is on. You feel lucky that you are still connected to the internet with your handheld; you start searching PhysLINK.com and there it is: Albert Einstein got his Nobel prize in 1921 for his work on the photoelectric effect! You get the extra points.

Lab is finished and you now check your schedule on your handheld; 7:00 pm date with Jenny - get some flowers.

Feeling enriched by the eternal knowledge of the photoelectric effect and excited by your date, you happily bounce to your dorm with your handheld PC in a pocket - it was a good investment!

End of story. Well, not yet...

In a not so distant future, students and professional scientists will be seeing what was described in the above story on daily basis. Handheld PCs will become as widely used as ordinary calculators are today.

Soon, we will carry our digital lab notebooks, plot and analyze our data, access any physical constant and solve any differential equation we need to, right on the palm of our hand, anywhere, anytime.

- Anton Skorucak, President and creator of PhysLINK.com

Reprinted with permission from PhysLINK.com

All rights reserved. Copyright '95-'00 PhysLINK.com

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