Science

Viva la curiosity, Viva la science! A game of skittles can quickly become a physics toy - as can a swing. Many, sometimes expensive, measuring devices can be built in the home workshop, such as the Hall probe for measuring magnetic fields. But it’s not just physics that is in the foreground here, but also chemistry and biology - so a walk in the forest can definitely become a research project.

Measuring the fitness trail

And things turn out differently!

Athletes and passionate walkers, almost all of Rüsselsheim know it: the Rüsselsheim fitness trail or Vita-Parcours. It is located near the forest swimming pool, a center of enthusiastic swimmers in summer.

Whether jogging, easy running or walking, everything is done here. Some people also use the training exercises, which are a few hundred meters apart. These include sit-ups, push-ups, climbing stairs, various exercises for jumping, climbing and much more. But what is completely unknown is: how many kilometers does it count?

If you run the fitness trail, you know what you have achieved and can go home happy, while leisure joggers are only peripherally interested in running speed and distance. Nevertheless, how often do you hear joggers discussing the length? This often escalated into a small argument. Is it longer than 3 kilometers or not?!

Schreiber, feeling like one, tackled the issue as follows. Firstly, you cycle the trail with a bike and speedometer, but you only get inaccurate measurement results, which, as we will see later, differ drastically from the actual value. Secondly, you use a GPS receiver (Garmin Geko 201) and you will find that the dense forest means there are sometimes too few satellites, which makes measuring almost impossible. So what is as accurate as possible, but not dependent on satellites? Exactly! Thirdly: a steel disc bike. This is a bike that you push in front of you while running and measures the distance precisely, or better yet, to one meter per kilometer.

Interesting: If you compare the distance given by the bike with that given by the GPS receiver, you will find a relative error of around 20%. In concrete terms, this means that the GPS receiver only shows 80 percent of the actual distance, at around 3,590 meters!

If you now always measure in the middle of the path, without the two shortcuts on the path, you get a length of around 4.2 kilometers! That is much more than anyone would have estimated.

The complete measurement protocol can be found here.

If you have asked yourself the same question, the article has helped you or you have carried out a similar measurement, Schreiber would be happy if you contacted him via this link.

To create an overview map of the path in Google Earth, the kml file can be downloaded here. The thumbtacks mark the exercises. If you click on one, the description opens. The coordinates were determined with a GPS receiver and with an accuracy of 12 meters radius. “TDP” stands for “Trimm-Dich-Pfad”. A little further down you will find the description of all the exercises.

Writer of this refers to the report on myheimat.de and thanks for the kind mention.

Have fun exercising!

Hall probe

The interaction of electricity and magnetism is present everywhere in today’s technology and we all benefit from it all the time. Be it in cars, computers or of course television.

However, we humans have no direct senses for these phenomena. In measurement technology, a so-called “Hall probe” is used, which uses the effect of the same name. If an electric current flows on a conductive plate, it is deflected sideways in the magnetic field, so that a voltage is measured on both sides of the plate, which can be used to determine the magnetic field. It sounds complicated, but it isn’t. To build it, you actually only need leftovers: a piece of sheet metal that is as thin as possible, 4 wires and a hot soldering iron.

The image with the Hall probe was used in the textbook “Abitur 2017 Hessen: Physics”, which was published by Stark Verlag and helps high school graduates prepare for their high school exams.

Camera Obscura

Social interactivity using the example of a camera obscura

Recently, while cleaning out remote cupboard areas, the author came across a long-forgotten utensil. If you look at the picture above, you immediately think of a piece of sewer pipe from the nearest hardware store. That would be correct, if the author, as a 7th grade student, had not had the idea of rebuilding the camera obscura he had just covered using the resources available. The act of creation initiated by this is intended to document the complex interactivity of various social areas. A quiet smile from the reader is certainly welcome!

While the scientist ponders the physical laws and sets basic parameters, the businessman signals a minimal budget, so the designer sneaks through the basement to find suitable ideas for implementation, which are then included in a parts list after comprehensive morphological analysis.

The procurer, buyer then procures the “valuable” parts such as the tube (sewer pipe), ground glass (greaseproof paper), light-tight panels (black cardboard) and various small items such as glue and tools, if possible from the family’s existing stocks.

After cutting the sewer pipe with his father’s hacksaw, the first technical defects become apparent, the cut looks as if a beaver had gnawed it. So the usual solution for a 12-year-old comes into consideration: clean dressing on the lathe at home. Since the father responsible for this is of course difficult to enthuse, the politician comes into play. “Dad, I’m going to go down to the basement and get the lathe ready” usually triggers an immediate reaction that brings the goal closer. Experience shows that it is much more effective if you rephrase this message and pass it on to someone else: “Mom, can you tell Dad that I’m in the basement getting the lathe ready…” It’s easy to see that the politician is a socially important person. When Dad then inevitably discovers the sewer pipe that he bought for some other, in his opinion more important, matter, it’s up to the lawyer to interpret the family rules skillfully and avert an impending trial in family court with the threat of pocket money being deducted.

Once this hurdle has been overcome, the craftsman carefully assembles the parts and then hands the result over to the aforementioned scientist, who determines that the optical performance is excellent for imaging various burning candles, but that for other objects it is outshone by any disposable camera. This is the moment for the marketing specialist, who determines that there is definitely no market for this part, as it is completely unnecessary for the masses. So an advertising expert is called in, preferably from the cosmetics industry, who generates huge demand by cleverly choosing an advertising slogan “the cult item that Goethe loved, in a limited edition for a ridiculous €19.95” and generous placement of advertisements, spots, etc., which is made possible with professional help from graphic designers and film directors. The use of a well-known actor from the action scene - names will not be mentioned here - proves to be a resounding success. This huge demand can of course only be satisfied by industrial production overseas. The professions, arts and sciences involved will be covered in Part 2, the printed version of which can be easily transported on a medium-sized semi-trailer.

Biology

Electron microscope - The cell

Small things, big things. During the autumn holidays, Schreiber learned about cells and how to observe them. The research was summarized in two presentations.

The Internet offers very good information material about electron microscopes. There is a lot to be found, especially in the image sector. Images from an EM, TEM or SEM are unique and fascinating. See for yourself!

Chapter 5 of our 11th grade textbook catalogues the individual cell components, called organelles, in detail. There are also good images here. With the text from the book and high-resolution scans, the presentations are suitable for projectors.

The great thing about the whole thing is that they can be used directly in class.

Osmosis and diffusion

… are on the full 11th grade curriculum. To introduce this topic, there was an experiment in which you have to cut potatoes in half and make a hole in them. The holes are then filled with salt, sugar and starch. The aim of the experiment is to determine relative osmotic values. This works well so far, but it takes time and you don’t see the processes.

The solution is simple.

After the experiment was set up, the processes were filmed for 30 minutes. The result was shortened to 2 minutes using time lapse. The collected results were summarized in a presentation. Now you can see exactly what is happening.

Leaves and bushes

Biology is alive! How can you fill biology lessons with experiments and independent work?

Even in grade 6, leaves and their fruits were searched for. Long walks through the forest were necessary to find the many different types of leaves. The correct assignment to the trees is not easy, and helpful parents and friends are at a loss. Plane trees can easily become chestnuts and vice versa.

During the 2006 summer vacation in the idyllic Black Forest, the idea came up quite by chance to repeat this major search and find the most important leaves and photograph them in high resolution. In the adjacent forest, there was a forest nature trail with labeled trees and bushes. Identification was not a problem, but a presentation with just labels and photographs is less informative. The information we were looking for about the objects was kindly provided by the local forester. He explained many details while being bombarded with questions.

The top image shows the finished DVD with all the images and the presentation, the middle one shows the rowanberry in the frontal view and the bottom one shows the well-known chestnut fruit.

The initial scope of 3-6 trees in the presentation quickly expanded to 30. All trees and bushes were photographed in 6 perspectives (branch, fruit, long shot, leaf, leaf from behind and trunk).

Let’s see if next summer will reveal other, still “undiscovered” trees and bushes.

Hydrometer

“Eureka! I’ve found it!”, were the (attributed) words of Archimedes. In this case, it helped us to determine the relative density of liquids.

“The buoyancy force of a body in a medium is exactly as large as the weight of the medium displaced by the body.”

The effect that is used here is called “Archimedes’ principle”. It is not only known because of its story with the alleged gold crown, but also because of shipping.

Here is a brief explanation: The reason for the buoyancy of bodies immersed in fluids (liquids) is the pressure difference between the edges of the body. The forces acting on the right edge cancel out those on the left, but not the forces acting on the upper and lower edges. Systems strive to establish equilibrium, which is why a body floats until the forces acting on it have balanced out.

It is not difficult to build your own density meter, also called a hydrometer. A tube that is closed on one side is fitted with a weight. The ideal weight is one or more cent coins. These coins must be glued to the bottom of this tube. The open side is then sealed with insulating tape. In order to make relative statements, i.e. this liquid has a higher density than another comparison liquid, you need a scale. A 10 centimeter long strip of graph paper is completely sufficient for this. Your own density meter is ready, as shown in the picture.

Calibration is extremely simple. What comparison liquid do you have on hand? - Water. Dip the hydrometer into a glass of water. Note that the glass must be larger or smaller depending on the size of the weight.

Example of use: Determining the sugar content when brewing beer!

Einstein Year 2005

100 years of Einstein, 50 years of the theory of relativity. That has to be celebrated - the IKS took that literally. In several themed evenings, laypeople were given more detailed information about Einstein’s ideas and elaborations. But that was not all. A theater project called “MIR” ran for several years. The idea was to implement relativistic effects in a play in a playful way.

What sounds simple is usually not. One thing is certain: over a long period of time, many different activities were carried out and offered, so a large bundle of knowledge was imparted in an entertaining, interesting way.

Second theme evening

Pure catastrophe!

In 2005, the Einstein year, we held monthly theme evenings to explain Einstein’s work. The highlight of this year was an excursion to the German Museum in Munich. The activities were to be documented via video recordings. So far so good.

The second theme evening was filmed by a high school graduate who unfortunately was unable to edit and finish the film because he started university. That’s the key word.

The lecture was without PA sound, the camera microphone was about 10 meters away from the speaker, the audio format was encrypted in a special Dolby Digital format. The full program!

Solution: The codec was decoded using various software upgrades and the audio quality was improved using DSPs (digital sound processors). The unpleasant background noises were masked by our own background music. The music had to be adapted to the plot. Thanks to Yamaha!

The editing was simple, but the effects shown, such as time dilation and the twin paradox, were visually prepared using flash animations and comments.

In terms of time expenditure, this film was the largest project to date… a year!

Information posters

Dr. Jörg Zaun, journalist, physicist and curator of the Berlin Einstein exhibition, gave a speech on the life and work of Einstein in the IKS auditorium on November 24, 2005. He entertained the numerous visitors with pictures, anecdotes and interesting facts about Einstein the man. He showed the researcher from a different perspective than usual.

We, the PhysiKANTs of the IKS, needed a break after the hour-long lecture to rebuild the stage. Food and drink were provided. To explain the theory of relativity during the break, we designed some posters and displayed them in the foyer. Schreiber was able to design eight large ones. Three of them can be found below as pictures.

Since this was not a direct school project, there was a lot of leeway in the layout. The content naturally had to be right too, and we worked well with the physics department, who helped us with the content corrections. It was a long development process until all the wording was right. The theory of relativity is not as difficult as you might think, but there was also “competent visitors” present that evening, so we had to work very carefully.

Since the printouts were done by a professional printer, we set the posters in professional layout software, which is also used to create books such as “Perfume”. In terms of positioning accuracy and color management, this cannot be compared to any office program.

Sound system in the auditorium

Premiere of the play “Murder on the Relativity Express”; November 24, 2005. The problem is obvious. The actors are quiet, the audience is loud, the auditorium generates strong feedback, and the play lives from acoustic effects. In other words, you need a sophisticated PA setup, consisting of microphones, mixer, equalizer, compressors, limiters, multigates, feedback reducers, delays, speakers, etc. So there are lots of opportunities to make mistakes. Thanks to the good input from Shure, it finally worked.

Using an UltraCurve device, the optimal room acoustics were specified and the target value was automatically compared with the actual value. A delay line was used to achieve a uniform sound pressure and avoid high levels. The sound pressure was always 10 dB higher than the disturbing background level. 10 dB means doubling the perceived volume.

The parameters and the effects were played using the laptop.

Murder on the Relativity Express

What happens when a few physics-loving students meet, a physics teacher comes up with a crazy preliminary concept and the whole thing happens in the middle of the Einstein year? Quite simply: Murder on the Relativity Express

This is a very special kind of play. A murder takes place on a train travelling at almost the speed of light. Due to relativistic effects such as time shift and length contraction, the police are at a loss. Two children, however, keep their eyes open and unmask the real culprit. A mad scientist, a not entirely faithful wife and a certain Lorentz family play the other roles.

The script, costumes, stage design, direction etc. were thought up and made by the group themselves. Due to a lack of acting talent, my job was sound and video editing.

Three simultaneous camera images from different perspectives, as well as externally recorded sound from six microphones made the lip-sync editing tricky. Since the projector image of the key scene in the video was too dim, overlay sequences of the original animation had to be inserted into the film. This was only possible due to the immense pressure of a stubborn teacher who would not accept excuses. At this point, many thanks for the kicks! - Now you can.

As the acoustics in the auditorium are terrible, we now know exactly what feedback is.

In addition to the premiere in the auditorium, we performed the play again in a modified form. This was used for the application video for the well-known Science-on-Stage competition. We put a lot of effort into the design of making-of folders, booklets and covers. Unfortunately, we were told that we couldn’t make it to the final round. It’s a shame, but what the heck?!

Despite everything, this video will remind us of the joy and friendship we had back then, even in 30 years. We donated a copy to the school archive.

Skittles

Want to go skittles without having to travel?

Isn’t that possible? It is possible with a 20x20 cm skittles game.

On a sanded, square wooden board, a 20 cm long wooden rod is mounted vertically on a corner. The upper end of this rod is drilled through and an aluminum tube, also 20 cm long, is inserted into it so that the wooden rod and the aluminum tube are at a 90° angle to each other.

The tube is parallel to the square wooden board. A 15 cm long piece of mason’s line is attached with a tight knot. The second end is attached to a ball, preferably made of iron, using a knot or screw.

Floor markings for the positions of the figures must be placed on the square wooden board. To do this, print an adhesive film.

Finally, you need the cones. Eight of these cones must be exactly the right size. 5 centimeters is ideal. To get a typical head shape, you can also decorate the figures with notches. The king should be one centimeter taller.

A parking station on one corner makes it easier to set up the figures.

Ready, set, go!

Lorentz swing

An old kitchen board, cable, battery… … and a magnetizer for screwdrivers are certainly not the classic components of a Lorentz swing. But amazingly, it works.

If a charge, for example an electron, moves in a magnetic field, a lateral force acts on it, which deflects it.

In our case, electrons flow through a cable inside the magnet and the wire is deflected like a swing (middle picture). If the circuit is interrupted, the wire swings back.

This lateral force is called Lorentz force.

The measuring devices are used to display the applied voltage and the flowing current. They are not actually necessary, but they are a decorative, optical counterpart to the wooden board. As we all know, the eye also investigates!

Mathematical helpers

For several years now, students have been enjoying the permitted use of so-called CAS inside and outside of school hours. CAS calculators, which stands for computer algebra system, can, in contrast to “normal” calculators: solve equations, display graphs and run (self-programmed) programs. This optimizes and simplifies time-consuming processes and visualizations of mathematical objects. One example of a CAS calculator is the TI Voyage 200. The Casio fx-9750G Plus, which is often used in schools, is a graphic calculator and not a CAS.

In astronomy, the same calculations often have to be repeated at regular intervals, for example to calculate the position of the sun using the shadow of a stake stuck in the ground. Although not difficult, these calculations take time. What *convenience if you only had to enter the parameter (shadow length) into the calculator and the result would be displayed automatically?

This is exactly where the CAS comes in. This efficiency can be achieved with a self-written program. By eliminating all programming errors, you penetrate the topic, which supports learning.

Six small programs are to be presented here, which the writer programmed on a TI Voyage 200. They are listed below as a download. Using this “software” requires the Voyage 200, the current OS, the connection cable and the TI Connect software. The transfer takes place as usual.

Anhang

Saturday Morning Physics 2008

For 8 Saturdays we were allowed to be guest students at the renowned Technical University in Darmstadt. Also called Saturday Morning Physics. The unusual narrowness of the “large physics lecture hall” on the one hand and the high quality of the learning content on the other were new and took some time to get used to. It was clear that the professors were deeply involved in the subject matter and answered our questions with professional ease that commanded respect. You couldn’t help but ask yourself, can I really study there? Can I even manage it? The reassuring fact remains that others have managed it and - as we hear - professors were once students too. That gives us hope. In any case, it was an excellent opportunity to experience everyday student life without the lens of a purely informational event, Rating: definitely worth emulating!

Lecture content:

From the atomic nucleus to the supernova The synthesis of the elements

Building blocks of the universe In search of the indivisible

Nuclear fusion Limitless energy from water

Light Hot bodies and cold atoms

Quanta with the highest energy Humans under constant attack

Supernovae We are all stardust

Neutron stars A journey into the past

A big bang in the laboratory Matter at very high densities and temperatures