1910-1929

Scientists' understanding of the structure of the atom and of its component particles grows, the phone and radio become common, and the modern television is born.

1911

Superconductivity discovered

German physicist Heike Kamerlingh Onnes discovers that some materials exhibit almost no electrical resistance when they are cooled to extremely low temperatures, a phenomenon referred to as superconductivity.
1911

Alpha rays & atoms

Under the direction of Ernest Rutherford, Hans Geiger and Ernest Marsden carry out numerous experiments on the scattering of alpha rays, leading Rutherford to posit a new model of the atom.
1912

Mercury lamps

High-pressure mercury lamps are invented, but do not become commercially available until more than 20 years later.
1912

Regenerative circuit

While still a student at Columbia University, Edwin Armstrong invents the regenerative circuit, which enables amplification of a signal many times by the same vacuum tube.
1912

X-ray secrets

German physicist Max von Laue proves that x-rays are electromagnetic in nature.
1915

First cross-country call

Thanks to American inventor Lee De Forest's audion, telephone signals are able to be carried across country, making possible the first transcontinental phone call between San Francisco and New York.
1919

Barkhausen effect

German physicist Heinrich Barkhausen discovers that a ferromagnetic material to which an increasing magnetic field is gradually applied is magnetized in small steps rather than on a continuous basis. Known as the Barkhausen effect, this phenomenon provided clear support for the theory of ferromagnetic domains.
1919

Superheterodyne circuit

American inventor Edwin Armstrong invents the superheterodyne circuit, providing the broadcasting industry a greatly improved way to receive, convert and amplify weak, high-frequency electromagnetic waves.
1919

New kind of magnet

Quench-hardened steel magnets are introduced commercially.
1919

Electricity in the body

English electrophysiologist Edgar Adrian demonstrates that nerve cells generate voltages that trigger muscle contractions.
1920

Tune into KDKA

The first radio broadcasting station in the world, station KDKA in Pittsburgh, Pennsylvania, is launched by the Westinghouse Electric and Manufacturing Company.
1922

Neon tubes

Neon tube lighting becomes available commercially and is especially popular for advertising purposes.
1922

Space quantization

German physicists Otto Stern and Walther Gerlach demonstrate through the use of a molecular beam that the spatial orientation of atomic particles in a magnetic field is restricted (a concept termed space quantization).
1923

Iconoscope

Russian inventor Vladimir Zworykin files a patent for the iconoscope, the first completely electronic means of scanning a picture for television.
1924

Ising model

As part of his doctoral dissertation, German physicist Ernst Ising introduces a model, now known as the Ising model, to explain the behavior of ferromagnetic materials.
1925

Electrons spin

While graduate students in the Netherlands, George Uhlenbeck and Samuel Goudsmit postulate that in addition to their orbital motions, electrons spin about their axes.
1928

The antiparticle

British physicist Paul Dirac accurately predicts that there exists an antiparticle to the electron that has the same mass as the electron but the opposite electric charge and magnetic moment.
1929

Coaxial cable

American engineers Herman Affel and Lloyd Espenschied apply for a patent for coaxial cable, a transmission line for high-frequency signals that is characterized by low radiation loss and interference.
1929

Reversing polarity

Japanese geophysicist Motonori Matuyama studies the reversal of magnetic fields in rock strata and reasons that the Earth must occasionally undergo reversals of its polarity.
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