Students’ reasoning about the superposition of electric fields

This study concerns students’ ideas about the superposition of electric fields. Two paper‐and‐pencil questionnaires were given to university students to investigate possible obstacles to a correct use of this principle.

The results confirm an expected difficulty about Gauss's theorem, i.e., the idea that only ‘internal’ charges create a field on a given closed surface. Another more surprising finding is that students are reluctant to admit that a field can penetrate into, or go out of, an insulator, particularly because ‘charges cannot move’.

These first findings are discussed in connection with common features of students’ reasoning about mechanics and about multivariable problems. Some directions of future research are proposed.