1 | Teacher‘s Lab at CERN

Teacher‘s Laboratory

2 | Teacher‘s Lab at CERN

Teacher‘s Laboratory at CERN

• 5 classroom experiments– Cathode ray tube– Fine beam tube– Electron diffraction tube– Photoelectric effect– Electron spin resonance

• Video conference equipment

• Green wall

3 | Teacher‘s Lab at CERN

Cathode ray tube

• Study cathode rays• Deflection by electrical and (or) magnetic field• Cathode ray tube = electron accelerator• Example for oscilloscope and (no flat-screen) TV

4 | Teacher‘s Lab at CERN

Cathode ray tube

UA

Cathode Control grid Anode

Flourescent screen

5 | Teacher‘s Lab at CERN

Fine beam tube / Thomson-experiment

• Study Cathode rays.• Study Lorentz force.• Study of the deflection of electrons in a magnetic field into

a circular orbit.• Determination of the specific charge of the electron.

6 | Teacher‘s Lab at CERN

Fine beam tube / Thomson-experiment

Electron gun

Anode

Magnetic field (dipole)

7 | Teacher‘s Lab at CERN

Electron diffraction tube

• Determine the interplanar spacing of graphite using de Broglie relation and Bragg’s reflection

• Related topics and concepts:– Wave-particle duality (X-ray vs. electron)– Bragg’s reflection– Study small structure (inaccessible to optical)

8 | Teacher‘s Lab at CERN

Electron diffraction tube

UA

CathodeControl grid

Anode

Flourescent screen

Graphite foil

9 | Teacher‘s Lab at CERN

Photoelectric effect

• Verify the photoelectric effect.• Calculate Planck’s constant h• Show that the kinetic energy of the electrons is

independent of the intensity of the light.

10 | Teacher‘s Lab at CERN

Photoelectric effect

Cathode Circular Anode

V

High pressure Mercury lamb

Interference filters

11 | Teacher‘s Lab at CERN

Electron spin resonance

12 | Teacher‘s Lab at CERN

Electron spin resonance

• Model of electron spin resonance demonstrating the interaction between the magnetic moment of the electron spin with a superimposed direct or alternating magnetic field

• Related topics and concepts:– Larmor precession– Revise resonance, gyroscope (not main focus)

• Caveat– No classical equivalent to spin concept!– This is just to help student form some mental model