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Resonant cavities
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Metal boxes support standing EM waves.
Metal boxes support EM standing-wave modes at discrete frequencies; used in microwave ovens, lasers and particle accelerators. Resonant frequency f = (c/2)√((l/a)² + ...).
Magnetron cavities.
Modes depend on the cavity shape.
In more detail
A resonant cavity is an enclosed space that supports standing electromagnetic waves at particular frequencies. Microwave ovens and lasers use resonant cavities to store and amplify energy.
Real-world uses
- Magnetrons in microwave ovens use resonant cavities.
- Lasers use optical cavities to build up light intensity.
- Microwave ovens and particle accelerators use metal cavities that support standing electromagnetic waves at specific frequencies.
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Frequently asked questions
What determines the resonant frequencies?
The dimensions of the cavity and the wave speed inside it.
Why do cavities matter for lasers?
They reflect light back and forth, amplifying it with each pass through the gain medium.
Why are cavities used?
They store the wave energy at a chosen frequency, which allows efficient acceleration or heating.
Related topics in AC Circuits & EM Waves
Lasers in communication · Electromagnetic shielding · Skin effect