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Is there any quick and easy way to determine if a microwave oven is leaking radiation from the door edges? By quick and easy I mean without buying a dedicated meter.
And if there is an undetected leak, how far do microwaves generated by a domestic microwave travel in air?
What wattage/cm^2? Microwatts? Attowatts? All microwave seals leak. They may act more like a -60dB attenuator, rather than a perfect reflector.
If you're only worried about microwave heating (burns,) then any straight fluorescent tube-lamp will light up when held against a watts-scale door leak. Or, hold the terminals of an NE-2 neon lamp with fingers, and pass the glass lamp over the door seals, watching for orange flash. This is the same as tesla-coil lighting of a fluorescent tube. (Heh, actually a microwave oven chamber is a driven high-Q resonator. So in that sense the oven IS a 2.5GHz tesla coil.)
If instead you're looking for a high-milliwatts leak which might overload a receiver front-end, or perhaps hurt some sensitive electronics, then Tony_Stewart's trick with the red LED works fine. Simpler: two red LEDs soldered back to back in parallel, so both will light from AC. Add a 2" floating wire to to one side, hold the other with fingers as a ground, then pass the wire near the seal and watch for LEDs to glow.
I once took apart an active oven-leakage detector having a separate probe. The probe itself was a tiny pcb with a 1" ring trace, with six 1N4148 diodes soldered in a radial array, positive terminal pointing inwards to a central contact. The ring was ground, the pos terminal led to a resistor load and a 741 op amp. Obviously it was acting as a small loop, a nearfield probe-antenna with a diode detector. But they'd added five more in parallel, so the device would read roughly the same e-field regardless of probe orientation.
Spread the leads of a 5mm LED with zener protection into a dipole and hold the lens with leads next to the seam. If there is any dim glow then you have leakage.
If you put inside oven and turn on it will explode the lens off with a big pop.
Put a cc of mixed water/fat on the external seam. It must remain cold.
Or try this:
simulate this circuit – Schematic created using CircuitLab
how far do microwaves generated by a domestic microwave travel in air?Microwaves aren't magic, they are radio waves at about the same wavelength as WiFi. So the loss due to the atmosphere in dB will be roughly 20*log(distance in m) + 40. \$\endgroup\$