* Electric and Magnetic Fields: Charged particles create electric fields. When they move, they also create magnetic fields.
* Accélération: When a charged particle accelerates (speeds up, slows down, or changes direction), the electric and magnetic fields around it change as well.
* vagues: These changes in the fields don't happen instantaneously. Instead, they propagate outward from the accelerating charge like ripples on a pond, forming an electromagnetic wave.
Exemples:
* Light from the Sun: The Sun's core contains charged particles that are constantly accelerating, generating light.
* Radio waves from antennas: Radio antennas use electrons moving back and forth (accelerating) to create radio waves.
* Microwaves in your oven: Electrons in the magnetron accelerate and generate microwaves.
* X-rays from medical machines: Electrons are accelerated to high speeds and then abruptly stopped, creating X-rays.
Points clés:
* Fréquence et longueur d'onde: La fréquence (à quelle vitesse les ondes oscillent) et la longueur d'onde (la distance entre les crêtes d'onde) des ondes électromagnétiques sont déterminées par l'énergie des particules chargées accélérées.
* Spectre électromagnétique: The entire range of electromagnetic waves, from low-frequency radio waves to high-frequency gamma rays, is called the electromagnetic spectrum.
En bref, les ondes électromagnétiques sont une conséquence de l'interaction fondamentale entre les charges électriques et les champs électriques et magnétiques qu'ils créent.
