High School Teachers





New ways of Doing Familiar Experiments

Foam chamber

Simple Hertz Experiment

Home made GM counter

Half life game

Home made cloud chamber

Home made spark detector


Collecting radioactivity

Measuring the size of molecules

1.)  Foam Chamber

What we do need:      A box, with an open top (size: 20cm x 10 cm x 1cm) plexiglass 
                                  Stable foam from any detergent
                                  Radioactive source 

What we do:             Fill the box full of foam
                                 Force the source above the box
                                 Observe the surface of foam

        What we can learn:       How long is the free way of alpha radiation
                                            The slow particle is effective
                                                             (idea: Kawakatsu Hiroshi, Japan) 


2. Simple Hertz Experiment


    What we need:     A cardboard
                               Two aluminum foil sheet 10cm x 6cm 
                               Four pieces of copper wire ( about 7 cm) each
                               A little Glimm bulb (from phase detector) 
                               Stove igniter (piezoelectric) 

    What we do:      Radio signal sender
                              Glue the two aluminum foil sheets to the carton
                              Glue the two wire to the foils (see the figure) 
                              Connect them with the gas lighter


                               Solder the two other wires to the end of bulb

                               Push igniter, this will create sparks in the gap
                               Close the receiver, and the bulb will lightening

        You can make a diffraction grating from aluminum foil, and study the polarization of waves

    What we can learn:  The principle of a Nobel prize experiment of Heinrich Hertz.

                                                            (idea: Stray Cats, Japan) 


3.)     Home made GM counter


    What we do need:     Two film tubes (plastic tube, that film comes in) 
                                     Wire, paper, gas (from gas lighter) 
                                     Aluminum Foil, screw
                                     Pocket radio

    What we do:             Make two holes in the first film tube (see the figure) 
                                     Put wires trough them
                                     Put paper cylinder in the can
                                     Fill with gas (from gas lighter), and close it
                                     Make a capacitor (see the figure) 
                                     Connect the capacitor to a counter
                                     Tune your pocket radio to static- no channels
                                     You can listen the discharges due by particles on the radio

     What we can learn:     The structure and principle of GM counter
                                                                       (idea: Kawakatsu Hiroshi, Japan) 


4.) Game for to study of half life

    What we need:        Coins or dice

    What we do:          Have your class stand up
                                  All the students have a coin
                                  At the same time they should their coins all throw up
                                  Those who threw a head, should sit down
                                  Repeat it, and take down #`s. 
                                  You can change the ratio of probability with dice

     What we can learn:     The random process is not chaos either. 


5.) Home made cloud chamber

            What we need:          A heatproof glass bowl
                                             A dark piece of cotton, or silk
                                             Dry ice Alcohol Sponge
                                             A piece of transistor cooler
                                             Any charged object
                                             Desk lamp
                                             Tiny radioactive source (beta or alpha) 
            What we do:              Put dry ice in a plastic box
                                             It must be broken, and a little alcohol poured onto it, and then put in the
                                             transistor cooler
                                             Pour a little alcohol (1-2 ml) onto a sponge around the bowl, put in the
                                             source in the bowl. 
                                             Tightly wrap the top with plastic wrap
                                             Put a bowl onto the transistor cooler
                                             Wait a little bit, for the alcohol evaporate
                                             Pass the charged object over the top of the wrap to clean the field of other

         What can we learn:       The principle of diffusion cloud chamber
                                                                                                (idea: Mori Yuji, Japan) 



Plastic wrap

Sponge glued around to sides of bowl

Heatproof bowl
Any dark synthetic textile

Heat insulator box (plastic foam) 

Dry ice


6.) Spark detector

    What we need:          3000 V DC  (see the figure) 
                                    A metal plate
                                    A wire (see the figure) 
                                    Radioactive source

    What we do:           Join the detector to a voltage
                                   Put a source above it. 

    What we can learn:     The principle of spark chambers
                                                     (idea: Shiniichi Kishizawa) 


7.) Spectroscopy

        What we need:         Stiff paper, plastic diffraction grating

        What we do:            Cut out from the stiff paper the body of spectroscope (see the figure). 
                                        Make a round hole at the end of the tube (30 cm x 2,5 cm), and slit at the
                                        other end. 
                                        You can glue the grating to the inside of the hole, and prepare the tube. 
                                        When you look through the hole, at the bottom of your viewing screen you will
                                        see a spectrum. 

                                        If you have a bigger piece of grating, you can take a photo of a spectrum too. 
                                        Put the grating on a stable frame. 
                                        In a dark room you can find the spectrum, and take a photo. You must 
                                        experiment with the exposure time. 
                                                                                      (idea: Yanchai Yingprayoon, Thailand) 


8.) Collecting  radioactivity in the classroom 

    What we need:              A toy balloon 
                                        A Geiger-Muller counter 
                                        A  glass 

     What we do:               Blow up the balloon 
                                       Give it a charge (with silk, or with the hair of a longhaired girl)
                                       Put it on the glass on the floor (insulator) 
                                       Wait 30 minutes until and let the balloon deflate 
                                       Hold the balloon up to the counter 
                                       Compare the count of impulses with the background 


      What we need:           Vacuum cleaner 
                                        Six layer of medical gauze, rubber ring 
                                        A Geiger-Muller counter 

    What we do:                We force the gauze to the end of the tube of vacuum cleaner. 
                                        Run the vacuum in the basement or in another poorly ventilated area 
                                        Take the gauze, and you can measure the radioactivity 

    What we can learn:      We live in continuous radiation. 



9.) Measurement of size of molecules 


    Introduction     The molecule: oleic acid, a long particle with one end hydrophilic, another - 
                            hydrophobic. It does not dissolve in water, but when a drop of oleic acid is put on 
                            the water surface it spreads out into 
                            Mono molecular layer (if it has enough place - one drop needs a surface of swimming 
                            pool!) To make an experiment possible in  school lab one has to dissolve  oleic acid in 
                            ethanol - which can be done without any restrictions. 
                            The best results are obtained in a 0.5% (volume) solution. 

    What we need:  oleic acid, ethanol, measuring cylinder, container to prepare solution, pipette 
                            (0.5 - 1 ml), cuvette, tap water, some fine powder, ruler . 

    What we do:          1. Prepare solution; 
                                  2. Fill the cuvette (like for developing pictures) with water and spread fine powder 
                                  light on its surface. 
                                  3. Using the pipette put one drop of solution on the surface; 
                                  4. Using the ruler measure the size of the oleic acid layer; remember, the ethanol 
                                  will dissolve in water. 
                                  5. Knowing how much the real volume of oleic acid was and what the size of layer 
                                  is you can calculate the size of the molecule. 

                                    Note: the size of the layer is about 20cm x20cm. 

CERN and High School Teachers Programme at CERN

Last modified: 28 June 2002