Question

radius of a pencil lead in standard foam

Answer 1

Answer:

Diameter. Mechanical pencil mechanisms use only a single lead diameter. Some pencils, such as the Pentel Function 357, place several mechanisms within the same housing, so as to offer a range of thicknesses (in this case three: 0.3, 0.5 and 0.7 mm). 1.00 mm leads also exist, but they are very rare.