One form such a detector takes is the bolometer.
Rutherford invented a magnetic detector depending on the power of electric oscillations to demagnetize iron or steel.
This device was converted into an electric wave detector as follows :-The mercury-steel junction was acted upon by the electromotive force of a shunted single cell and a siphon recorder was inserted in series.
Rutherford used this detector to make evident the passage of an electric or Hertzian wave for half a mile across Cambridge, England.
It was then proposed to arrange a detector so that it was affected by the algebraic sum of the two oscillations, and by swivelling round the double receiving antennae to locate the direction of the sending station by finding out when the detector gave the best signal.
Marconi applied a modified and improved form of Branly's wave detector in conjunction with a novel form of radiator for the telegraphic transmission of intelligence through space without wires, and he and others developed this new form of telegraphy with the greatest rapidity and success into a startling and most useful means of communicating through space electrically without connecting wires.
An innumerable number of forms of coherer or wave detector depending upon the change in resistance produced at a loose or imperfect contact have been devised.
Wilson constructed various forms of electric wave detector depending on this same principle.
Fleming invented in 1904 a detector called an oscillation valve or glow lamp detector made as follows: 1 A small carbon filament incandescent lamp has a platinum plate or cylinder placed in it surrounding or close to the filament.
- Telluriumbismuth Vacuum Thermal Detector for Electric Oscillations.
Her hair was drawn back severely into a bun and she had black eyes that could render a lie detector machine obsolete.
He employed as a detector of this wave a simple, nearly closed circuit of wire called a Hertz resonator, but it was subsequently discovered that the metallic microphone of D.
Rutherford examined it very carefully, and produced a magnetic detector for electric waves depending upon the power of electric oscillations in a coil to demagnetize a saturated bundle of steel wires placed in it.
In 1902 Marconi invented two forms of magnetic detector, one of which he developed into an electric wave detector of extraordinary delicacy and utility.
When used as a receiver for wireless telegraphy Marconi inserted the oscillation coil of this detector in between the earth and a receiving antenna, and this produced one of the most sensitive receivers yet made for wireless telegraphy.
Other forms of magnetic detector have been devised by J.
Fleming, " A Note on a Form of Magnetic Detector for Hertzian Waves adapted for Quantitative Work," Proc. Roy.
A fourth class of electric wave detector comprises the thermal detectors which operate in virtue of the fact that electric oscillations create heat in a fine wire through which they pass.
He therefore saw that it was a mistake to insert a potential-affected detector such as a coherer in between the base of the antenna and the earth because it was then subject to very small variations of potential between its ends.
In the same way the arrangements finally elaborated by Lodge and Muirhead consisted of a direct coupled antenna and nearly closed condenser circuit, and a similar receiving circuit containing as a detector the steel wheel revolving on oily mercury which actuated a siphon recorder writing signals on paper tape.