Although we cannot see magnetic field lines, we can detect them using iron filings. The tiny pieces of iron line up in a magnetic field.

Zeeman for the observation that when a source of light is placed in a strong magnetic field the spectral lines of the light emitted by that source suffer marked modification. The general type ...

A magnetic field is invisible ... different positions in the magnetic field, marking the needle direction each time join the points to show the field lines The needle of a plotting compass ...

The transfer manifested as a small beam of accelerated barium electrons heading toward Earth along the magnetic field line. The beam is visible only in the experiment's magnetic field line data.

Polarised light oscillates, which allows astronomers to “see” the particles around the black hole swirling around magnetic field lines to create a distinct pattern. The observations were made ...