Microwaves: The Faraday Cage

Your microwave blasts 1000 Watts of 2.4GHz radiation (the same frequency as Wi-Fi) to boil water. If that leaked out, it would boil your eyes (and kill your Wi-Fi). Look at the glass door. It has a metal screen with holes. Why doesn’t the radiation escape through the holes?

The Wavelength Rule

• Frequency: 2.45 GHz.
• Wavelength: ~12 centimeters. The holes in the mesh are ~2 millimeters. Because the hole is smaller than the wavelength, the wave treats the mesh as a solid wall. This is a Faraday Cage.

Shielding Robot Wires

In robotics, we have noisy motors (creating magnetic fields) right next to sensitive sensor wires.

• The Noise: The motor field induces “Ghost Voltages” in the sensor wire.
• The Fix: We twist the sensor wires (Twisted Pair) and wrap them in foil or a metal braid. This metal braid acts as a Faraday Cage for the wire.
• External noise hits the shield and travels to ground.
• The signal inside remains pure. It’s the same physics that keeps your Hot Pocket hot and your Wi-Fi router safe.