Electromagnetic Radiation
Wave or Particle? continued...
In brief, when an electron returns to a lower energy level, it is thought to give off a tiny "packet" of energy called a photon. The amount of energy in a photon may vary. It depends on the frequency of electromagnetic radiation. The higher the frequency is, the more energy a photon has.
microwave
Microwaves are a familiar example. They are a type of electromagnetic wave that you can read about later on in this chapter, in the lesson "The Electromagnetic Spectrum." When microwaves strike food in a microwave oven, they are converted to thermal energy, which heats the food.
How Electromagnetic Waves Travel
The electric and magnetic fields that make up an electromagnetic wave occur are at right angles to each other. Both fields are also at right angles to the direction that the wave travels. Therefore, an electromagnetic wave is a transverse wave.
Electromagnetic radiation
The transfer of energy by waves traveling through matter or across empty space.
No Medium Required
Unlike a mechanical transverse wave, which requires a medium, an electromagnetic transverse wave can travel through space without a medium. Waves traveling through a medium lose some energy to the medium.
How Electromagnetic Waves Begin continued...
You can learn how this happens in the chapter Electromagnetism. The two types of vibrating fields combine to create an electromagnetic wave.
Electromagnetic waves
a wave that consists of vibrating electric and magnetic fields.
Electric field
An area of electric force surrounding a charged particle
Magnetic Field
An area of magnetic force surrounding a magnet
How Electromagnetic Waves Begin
An electromagnetic wave begins when an electrically charged particle vibrates. When a charged particle vibrates, it causes the electric field surrounding it to vibrate as well. A vibrating electric field, in turn, creates a vibrating magnetic field.
Lesson Summary
An electromagnetic wave consists of vibrating electric and magnetic fields. An electromagnetic wave begins when an electrically charged particle vibrates.
Wave or Particle? continued...
As evidence accumulated for this dual nature of electromagnetic radiation, the famous physicist Albert Einstein developed a new theory about electromagnetic radiation, called the wave-particle theory. This theory explains how electromagnetic radiation can behave as both a wave and a particle.
Wave or Particle?
Electromagnetic radiation behaves like waves of energy most of the time, but sometimes it behaves like particles.
Wave Interactions
Electromagnetic waves can travel through matter as well as across space. When they strike matter, they interact with it in the same ways that mechanical waves interact with matter. They may reflect, refract or diffract (bend around objects).
No medium required continued....
However, when an electromagnetic wave travels through space, no energy is lost, so the wave doesn't get weaker as it travels. However, the energy is diluted as it spreads out over an ever-larger area as it travels away from the source.