1930-1939

New tools such as special microscopes and the cyclotron take research to higher levels, while average citizens enjoy novel amenities such as the FM radio.

1930

Permanent alloy magnets

The first permanent alloy magnets of aluminum, nickel and cobalt (alnico magnets) are produced.
1931

Superconductors and insulators

British physicist Alan Wilson applies the band-gap theory of energy to account for the behavior of superconductors and insulators.
1931

Frst cyclotron

The first cyclotron, a circular particle accelerator in which subatomic particles are accelerated by an alternating high-frequency electric field in a fixed magnetic field, is built.
1931

First electron lens

German physicist Ernst Ruska, while still a student in Berlin, constructs the first electron lens, using an electromagnet to focus a beam of electrons just as a lens focuses a beam of light. By 1933, he uses several electron lenses in a series to make the first electron microscope with better definition than a light microscope.
1932

Discovering the neutron

James Chadwick of England discovers the neutron, a particle with mass similar to a proton, but that does not have an electrical charge.
1932

Discovering the positron

American physicist Carl Anderson discovers the positron, a particle with mass similar to an electron, but with a positive rather than negative charge.
1933

Meissner effect

Walther Meissner and Robert Oschenfeld of Germany discover that as a material loses its resistance to electricity when its temperature is dropped below a certain temperature, the magnetic field inside the material is completely or partly expelled. Characteristic of all superconductors, this phenomenon came to be commonly known as the Meissner effect or the Meissner-Oschenfeld effect.
1933

Sodium vapor lamps

Sodium vapor lamps come into use to light highways.
1934

Tape recorder

German inventor Semi Joseph Begun constructs the first magnetic tape recorder used for broadcasting.
1934

Fluorescent lamp

The fluorescent lamp is introduced in Europe.
1934

Coiled-coil filament

In the United States, the coiled-coil filament is invented, resulting in brighter and more energy-efficient electric light bulbs.
1935

Audio recording

Magnetic tape for audio recording becomes available commercially in Germany following its introduction at the Berlin Radio Exhibition.
1936

Antiferromagnetism

French physicist Louis Néel develops the concept of antiferromagnetism, a temperature-dependent form of magnetism in which adjacent ions arrange themselves in antiparallel formations so that nearly no overall external magnetism can be detected.
1939

Earth & eddy currents

Walter Elsasser, a German-born American physicist, proposes that the Earth’s observable magnetic field is the result of rotation-related eddy currents in the liquid core of the planet.
More in this category: « 1910-1929 1940-1959 »