The wavelength of microwaves significantly affects their ability to penetrate materials. Here’s how:
- Longer Wavelengths (Lower Frequency):
- Microwaves with longer wavelengths tend to penetrate deeper into non-metallic materials like food, fabrics, or plastic.
- These waves are less likely to be absorbed quickly, allowing them to heat larger volumes more uniformly.
- Shorter Wavelengths (Higher Frequency):
- Shorter-wavelength microwaves are absorbed more readily by materials, especially those with water or other polar molecules.
- This makes them effective for surface or shallow heating but limits their penetration depth.
- Material Dependence:
- The exact penetration also depends on the material’s properties—such as moisture content, density, and electrical conductivity.
- For example, water-rich materials absorb microwaves quickly, reducing how far the waves can go inside.
- Metal vs. Non-Metal:
- Metals reflect microwaves regardless of wavelength, so penetration is blocked.
- Materials like plastic, paper, and glass often allow microwaves to pass through with little absorption.