Result seems a bit high, when considering this following advice from ChatGPT:
The resistance of aluminium window screen over 50 cm can vary enormously depending on how you measure it, because the screen is a mesh of many thin wires connected at numerous junctions.
As a rough estimate:
- Typical aluminium screen wire diameter: about 0.25 mm (0.010″)
- Aluminium resistivity: about 2.8 × 10⁻⁸ Ω·m
For a single 0.25 mm diameter aluminium wire 50 cm long:
Using:
- L = 0.5 m
- A ≈ 4.9 × 10⁻⁸ m²
gives:
- R ≈ 0.29 Ω
However, a screen mesh contains many parallel wires. If you connect probes 50 cm apart along one edge of the mesh, the effective resistance is usually much lower because current spreads through dozens of parallel paths.
In practice, for a piece of aluminium insect screen about 50 cm square, you might measure:
- Less than 0.1 Ω between opposite sides if contact is good.
- Several ohms or even tens of ohms if the oxide layer causes poor probe contact.
- An ordinary multimeter may simply show 0.0 Ω because the resistance is below its resolution.
If you’re measuring for antenna or radio astronomy experiments, the contact resistance between the meter probes and the aluminium oxide layer is often much larger than the actual resistance of the mesh itself. Scraping a small area bright with sandpaper before measuring gives a more meaningful result.
FURTHER REPESTED MEASURMENTS LATER THE SAME DAY AT LRO ON THIS ROLL OF ALUMINIUM MESH FROM ONE END OF ROLL TO OTHER LED TO RESULTS OF 0.0-0.2 OHM ONLY. THE DIFFERENCE WAS IN THE WAY I MEASURED THE RESISTENCE. PREVIOUSLY I ADDED IN CROCODULE CLIPS SO I COULD PHOTOGRAPH WHILST MEASURING. THE LATER RESULTS WERE FROM DIRECT CONTACT OF THE ORIGINAL MEASUREMENT PROBES THAT CAME WITH THE MULTIMETER WITH THE MESH, DEMONSTRATING THAT THE CROCODILE CLIPS HAVE AN INHEREBT RESISTANCE WHICH AFFECTS THE RESULTS.