The experimental proof that a changing electrical charge produces an electromagnetic wave is based on the fundamental principles of electromagnetism. One of the key experiments that demonstrated this relationship is known as the Hertzian experiment, conducted by Heinrich Hertz in the late 19th century.
Here's a summary of the Hertzian experiment and its key findings:
Generation of electromagnetic waves: Hertz set up a simple experimental arrangement that involved a high-voltage source, a spark gap, and a pair of conductive metal rods acting as antennas. When a high voltage was applied across the spark gap, a rapid discharge occurred, resulting in an oscillating electric current.
Detection of electromagnetic waves: Hertz placed a separate metal wire loop, called a resonant receiver, a short distance away from the spark gap. This receiver loop had a small gap in it, creating a small spark between its ends. When the spark gap discharged and produced an oscillating current, it induced a corresponding oscillating electric field in the receiver loop.
Propagation and measurement of electromagnetic waves: As the electric field in the receiver loop oscillated, it generated a corresponding magnetic field, and the two fields combined to form an electromagnetic wave. Hertz observed that this wave propagated through space, and he was able to measure its properties, such as its wavelength, polarization, and intensity.
Through his experiments, Hertz demonstrated that a changing electrical current, produced by the discharge of the spark gap, generates electromagnetic waves. He showed that these waves exhibit properties such as reflection, refraction, interference, and diffraction, similar to other forms of waves. Hertz's experiments provided experimental evidence for James Clerk Maxwell's theory of electromagnetism, confirming the existence and properties of electromagnetic waves predicted by Maxwell's equations.
Since Hertz's pioneering work, numerous experiments have further confirmed the relationship between changing electrical charges and the production of electromagnetic waves. Today, this understanding is fundamental to various technologies, including wireless communication, radio transmission, and many aspects of modern electronics.