| HALL EFFECT |
Although
the Hall Effect was first measured by Edwin H. Hall
as long ago as 1879, it still provides a most useful
technique for determining the sign of the species that
carry the electric current in a sample. As recently
as 1985 Klaus von Klitzing received the Nobel Prize
for his research on the Quantum Hall Effect. |
| DETERMINATION OF e/m RATIO |
The
ratio of charge to mass (e/m) for the electron was first
measured by J. J. Thompson in 1897 in a series of measurements
that essentially discovered the electron. In this experiment
you will persuade electrons to travel in circular paths,
a trick with applications in areas ranging from ionospheric
physics to particle accelerators and fusion generators.
|
| DIELECTRIC CONSTANT AND CAPACITANCE |
This
experiment introduces the technique of the 'bridge',
a null method that provides one of the most precise
measurement techniques. You will use it to measure the
dielectric constant of a liquid and a solid. |
| X-RAY DIFFRACTION |
The
discovery of X-rays by Röntgen in 1895 not only
revolutionised medicine, but also provided a source
of electromagnetic radiation with wavelengths much shorter
than those of visible light. (The discovery also won
Röntgen the Nobel prize in 1901). It was soon discovered
that X-rays could interact with objects of atomic dimensions
and thus provide a powerful technique for the analysis
of crystal structure. William Henry Bragg and William
Lawrence Bragg were awarded the Nobel Prize in 1915
for their research in this area. Diffraction studies
using X-rays played an important rôle in determining
that the structure of DNA involved a double helix, research
that won Crick and Watson the Nobel Prize in 1953. Nowdays
X-ray diffraction plays a major rôle in elucidating
the structure of molecules of biological interest. |
| THERMIONIC EMISSION |
Free
electrons are normally confined within a material at
room temperature because they lack sufficient thermal
energy to overcome an energy barrier (the work function)
that arises from the electrostatic attraction of the
positively charged nuclei. In this experiment the work
function is estimated by heating a metal to increase
the kinetic energy of the electrons and measuring the
rate at which electrons leave the surface. This process
of thermionic emission' is still used in electronic
devices such as valves and cathode ray tubes. |
| STIRLING ENGINE |
In 1816 Robert Stirling was granted a patent for a new type of hot air engine that used a confined gas as its working fluid. Although neglected for many years, people are now finding uses for these efficient engines. The advantage of the closed volume working fluid is that it can employ expensive or dangerous substances - hydrogen, helium or even liquid sodium. |
| RADIOACTIVE HALF-LIFE AND HALF-THICKNESS |
The
discovery of radioactivity by Becquerel in 1895 lead
ultimately, not only to a Nobel Prize in 1903, but also
to the realisation that atoms have an internal structure.
Radioactivity is now a valuable research tool in many
other disciplines, particularly in medicine and biology. |
| MAGNETIC RESONANCE |
Nuclear
Magnetic Resonance, a technique which can measure the
magnetic properties of nuclei, was developed independently
by Felix Bloch and Edward Purcell in 1946 and won them
the Nobel Prize in 1952. Their research has blossomed
into one of the most powerful experimental techniques
with extensive applications, not only in Physics, but
also Chemistry, Biochemistry and Medicine. |
