The Physics
Opus in profectus


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  1. The inductance of the tungsten coil in an incandescent light bulb is 20 μH at 60 Hz. Make a question out of this basic idea.
  2. Write something.
  3. Write something.
  4. Write something completely different.


  1. An inductive loop detector (ILD) is a device used to detect the presence of a vehicle in a particular place. They are commonly placed at the entrance to intersections and are used to control traffic signals. A typical ILD is a square loop of wire 1 m on a side buried 5 cm below the surface of the road. Round copper wires, 1 mm in diameter are frequently used.
    1. How many turns are needed to give a minimum inductance of 250 µH?
    2. What is the resistance of this loop?