Future Meetings…

June 2 (T) Museum of Science and Industry Ruth Goehmann

July 25-29 AAPT Summer Meeting, Univ. of Michigan, Ann Arbor http://www.aapt.org/

At our last meeting...

…at Lake Forest College, Scott Shappe welcomed us and introduced the first phenomena. Then Paul Dolan announced that NEIU has scholarship money for incoming freshmen next year. A Topical Conference for Advanced Labs for college will be held at University of Michigan at Ann Arbor from the 23 to 25 of July (prior to the Summer Meeting). The June 2nd meeting will be at the Museum of Science and Industry. We may have to pay for parking. Eileen Wild announced the start of the Saturday free Compton Lecture Series at University of Chicago starting at 11 am for the next nine weekends. The topic is Einstein’s Relativity to String Theory. Parking on weekends is free in the Parking Garage at 55^thand Ellis. David Sokoloff is having an Activities Based Physics Course this summer. For more information and to register see the URL http://uoregon.edu/~sokoloff/chaut1.htm Paul also brought to our attention the third annual acoustics workshop at Rose Hullman Institute this summer

http://www.rose-hulman.edu/~moloney/Meeks_Workshop_2009.htm . New teachers at the meeting introduced themselves: Marshal Hong, William Krepelin, Jermont Montgomery, Eunice Laguia, and Matthew Pennington were all in one of Paul Dolan’s courses at NEIU. Jeremiah Campion teaches at Maria High School.

Ann Brandon (Joliet West High School retired) brought out the Jensen Bar Award and described the early history of ISPP for which Harald was a founding father. Gerry Lietz had several pictures of Harald. He also showed a picture of Earl Zwicker who carried on the program after Harald retired. This year’s award was given to Mel Sabella (Chicago State University). Gerry reminded us that the SMILE site http://www.iit.edu/~smile/ had instructions how to make and use the Jensen Bar.

Mike Kash (Lake Forest College) was on sabbatical leave at Texas A&M last year working on ultra short laser pulses using principle of Mode Locking and as the light waves couple they become Phase locked. Driven coupled oscillator phase lock. He wondered how they phase locked. If he provided a coupling between driven non-linear oscillators that are set at nearly the same frequency they become phase locked. He cited an AJP article (Vol 70 p 992, 2002). It described an interesting demo to illustrate the phenomena. His machinist had constructed a Lucite platform that rested on two acrylic cans. He mentioned that two tin cans and a board would suffice. He placed a metronome (Whitner super mini, $75) on the platform and noted how the platform moved in reaction to the swing of the arm. He added a second metronome which he had set to nearly the same frequency but out of phase with the original metronome. With in a minute or so the two had synchronized their motion to be in phase. He added a third, fourth and fifth metronome and within a few swings each came into synchronous motion with the others. Mike cited several example of such phase locking in nature. Fireflies in a tree will synchronize to all flash simultaneously. People walking together will end up in pace with each other.

Jason Myeggenburg (Lake Forest College) had seen his demonstration at the University of Chicago. His machinist had made an acrylic vertical cylinder in which he had nested a second Mylar cylinder which he could rotate around on its vertical axis. He had filled thin gap between cylinders with glycerin. He then used a thin straw to lay a vertical line of glycerin colored with graphite. He rotated the inner cylinder and the line of graphite appeared to smear out in the glycerin. After three turns he stopped and reversed the direction of rotation. After three turns the graphite line appeared to return to its original form. Jason explained that he really wasn’t “unmixing” the fluids. He was merely returning the laminar layers to their original position.

Scott Shappe (Lake Forest College) demonstrated Faraday’s law of induction by passing a strong neodymium magnet through a coil (Remco Electronics) which was connected to a large demonstration analog meter. Scott lamented the fact that one cannot do this demonstration as effectively with the new lecture digital demonstration meters since the transient reaction is so short in time. He soldered a set of LED diodes to the leads of the coil, one red and one orange LED arranged in opposite directions. As the magnet entered the coil one LED lit and as the magnet exited the coil the other LED lit up. Neat! He told us that this was our giveaway for tonight. We would receive a coil with the direction of windings indicated by an arrow with LEDs attached and a strong neodymium magnet. A handout showed the wiring diagram.

Jeremiah Camion (Maria High School) brought out his new acquisition from a bicycle sale, an auto shifting ten speed bicycle. Attached to the rear wheel are three weights spaced symmetrically around the wheel amid the spokes. As the wheel rotates the weights put tension on wires that hold them in place. When the wheel speeds up the weights move to the outside of the wheel near the rim and the motion pulls on the wires to shift the gears to higher settings. This amazing vehicle cost him all of $40!

Pete Insely (Columbia College) in remembrance of Harald drew square on the board and then drew a square within angled to touch each side of the larger square making four triangles within the original square. He labeled the inner square C² He drew an adjacent large square and within that he drew square based on the contact point of one of the small triangles with the large square and called it A². He added a smaller square labeled B² based on the remaining length. The resulting diagram showed that the square areas obeyed the Pythagorean relation C² = A² + B² The SMILE site above has the details of Pythagorean’s Puzzle too.

Then Pete drew a square and challenged us to find the dimensions of the rectangle when added to the side of the square would produce a rectangle with the same aspect ratio as the added rectangle. He showed that the aspect ratio is 1 to 1.618033. Pete then wrote the first numbers of the Fibonacci series 1,1,2,3,5,8,13 where the next number in the series is the addition of the previous two numbers. He noted that the ratio of any two numbers as one goes higher in the series, converges on the same number. For example 377/233= 1618025. Pete did not know how or why these two numbers were linked. Hmm?

Tom Senior (Northwestern University) had bought a new piece of equipment, an inexpensive Spectrophotometer called Spectroviz ($400 fromVernier). Tom put a piece of fluorescent plastic in a cruet and passed white light through it. It displayed the part of the spectrum that is absorbed and transmitted. He showed us the red and blue filters from a set of 3-D glasses. The apparatus also included a light pipe attachment ($60) that one could point at a light source and observe the spectrum. He showed the spectra of red and green laser pointers. The red laser spectrum showed a peak in the red at 633 nm. The green laser peak centered around 532 nm. He tried to pick up the spectrum of an incandescent light to see if it reproduced a classic black body distribution. The spectrum showed several peaks rather than the expected bell shaped curve. A Compact Fluorescent light (CFL) had a pretty complex spectrum. Tom then pointed a green laser at his fluorescent cup and looked at the reflected light. What do you think he saw? Paul Dolan had a piece of green fluorescent fiber used at Fermi Lab to make detectors. Paul shown a white light onto the side of the fiber and Tom put the end up to his detector where the spectrum showed a response around the green wavelength. Tom pointed the detector at a white LED to show the three primary colors that it was composed of. Ocean Optic also sells a $1500 version. Tom had a string of Holiday LED light. As he swung them around we could see that they actually were flashing.

Andy Morrison (Northwestern University) realized why he felt connected to Harald Jensen when he found out that University of Northern Iowa. Andy recalled a demonstration that Pete Insley had done with the Glow Ball (from Educational Innovations $7). He swung the ball around and we could see the separation of colors. He related how one can nicely see the complimentary colors when you slow the motion down and let the flashes overlap. Andy thought about photographing the ball to see if he could capture the flashes. He showed us the results of his first attempts. He thought it would be an interesting challenge for students to actually measure the flash rate by playing with different shutter speeds. Andy speculated that one might be able to detect the effect of terminal speed by photographing the flashing ball in free fall. Pete suggested that terminal speed could be achieved quicker by throwing the ball horizontally into a sheet to catch it.

Paul Dolan (Northeastern Illinois University) brought a bottle of soda one of his foreign students showed him. Take the wrapper of the top and you find a puncture piece. A glass marble is lodged in the top of the bottle to seal it. To open the seal you have to push hard on the marble to shove it into the bottle. After you finish drinking the soda you are left with the empty bottle with the marble rattling around in it. What a unique sealing system.

Tung Jeong (Lake Forest College retired) related how Harald Jensen had hired him 1963. He pointed out the recent Physics Today cover featuring John Wheeler (1911 – 2008). The articles in that issue related stories from three phases of John’s life. The 1^st phase was as a particle physicist, the 2^nd phase as Theorist, the 3^rd phase resonated strongly with TJ. He retired from lecturing at LFC but not from teaching. Now he is teaching 6 year olds. One of the toughest things he has had to do recently was to speak to an all school assembly at St. Mary’s School in Lake Forest involving grades one through eight. He shared in John Wheeler’s conjecture that all the world is information. “Space is that which holds information.” TJ bought out an imaginary volume of space and asked us what it was. He shared with us that he is preparing a manuscript on how to teach advanced information to children. TJ likes to guide students through simple calculations to find the maximum density of information. Taking the Plank Length as the limit to resolution in length, the ultimate information density is calculated to be 10⁶⁶ bits per cm²or 100 (gigabyte to the 7^th power). JT reminded us that a hologram is representative of densely packed information. He then added to our giveaway by humorously slicing his imaginary space and handing out the pieces. Lastly he shared with us a publication he found when he was in London in April 2002, a New Scientist article “Why we all live in a Hologram”. He also pointed out the February Scientific American Issue in which they republished best articles of the year, one of which was entitled “Are You A Hologram?” With that the meeting was concluded.

From West/Northwest:

Take I-88, I-90 or I-190 eastbound until you reach northbound I-294 (heading toward Wisconsin).Take I-294 north to Dempster Street east. Follow Dempster Street approximately ten miles through the suburbs of Des Plaines, Park Ridge, Niles, Morton Grove, Skokie and Evanston. At Chicago Avenue in Evanston, turn left and go north. Main campus is approximately three-fourths of a mile north at Chicago Avenue and Sheridan Road. Tech is at 2145 Sheridan.

From North:

Take I-94 East south to Skokie Highway. Go south on Skokie Highway approximately a half mile to Lake Street. Turn left (east) at Lake. Follow Lake approximately four miles east into Wilmette. Turn right on Green Bay and Left on Noyes Street. This will take you directly to Tech.

From West/Southwest

If coming in on eastbound I-80, follow I-80 until the interchange with I-55; take northbound I-55 .Follow northbound I-55 until the interchange with I-90/I-94; take northbound I-90/I-94 (Kennedy Expressway).When I-94 splits from I-90, bear to the right, staying on I-94 W (Edens Expressway).Take I-94 W north to Dempster Street east (exit 37B). Follow Dempster Street east approximately five miles through the suburbs of Skokie and Evanston. At Chicago Avenue in Evanston, turn left and go north. Main campus is approximately three-fourths of a mile north at Chicago Avenue and Sheridan Road. Tech is at 2145 Sheridan.

From South/Southeast:

When I-94 splits from I-90, bear to the right, staying on I-94 (Edens Expressway).Take I-94 W north to Dempster Street east (exit 37B). Follow Dempster Street approximately five miles through the suburbs of Skokie and Evanston. At Chicago Avenue in Evanston, turn left and go north. Main campus is approximately three-fourths of a mile north at Chicago Avenue and Sheridan Road. Tech is at 2145 Sheridan.