Solution to task 472 from Chertov´s for extramural stud

Solution to task 472 from Chertov´s for extramural stud

472. On a cardboard frame with a length of l = 0.8 m and a diameter of D = 4 cm, a wire with a diameter of d = 0.25 mm is wound in one layer so that the turns fit tightly to each other. Calculate the inductance L of the resulting solenoid.