Use of Induction Coils With Cathode Ray Tube

Induction coils can be used to remove excess gas from cathode ray tubes during manufacture.

Cathode ray tubes (CRT) have been the source of scientific experimentation since before the beginning of the 20th century. Scientists used CRTs with an induction coil to determine that cathode rays are comprised of streams of electrons.

Early CRT Usage

In 1897, British Nobel prize winning physicist J.J. Thomson demonstrated that electrons were negative and could be deflected by magnetic and static influences. An induction coil was used to pass a current to a CRT which emitted electrons. A fluorescent screen on the side of the CRT allowed viewing of the electrons' path.

Biomedical Applications

American researchers, Gasser and Erlanger, recipients of the 1944 Nobel prize in medicine and physiology, used the CRT and induction coil and applied current to a detached nerve specimen to record the effects of a single electrical stimuli; the image was visible on the CRT. Lacking a camera during the experiment, the researchers traced the wave displayed on the screen.

CRT Development

Many researchers contributed to the development of the CRT. John Logie Baird, a Scottish businessman and inventor, demonstrated the first television to the British Royal Institution in 1926.

References

• National High Magnetic Field Laboratory: Electromagnetic Deflection in a Cathode Ray Tube
• The Biomedical Engineering Handbook: Recording of Action Potentials
• The 1944 Nobel Prize to Erlanger and Gasser
• TV History: Early Television Experiments -- Baird

Resources

• The Cathode Ray Tube Site: Ruhmkorff coils
• The History of Computing Project: John Logie Baird