Do the gravitational field lines exist

Lexicon: field line model

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General, direction, strength

With the Field line model can be shown in simplified form how a field works around a body. The model can be used for gravitational fields as well as electric and magnetic fields. The lines are always clearly defined, i.e. they do not divide or cross.


The field lines always run in one direction. Gravitational field lines for (massive) objects are practically straight lines that are aligned with the center of mass. At electric fields they start with a positive charge and end with the negative charge. At Magnetic fields the direction is defined as the north pole of a sample magnet aligns, i.e. from the north pole to the south pole.


The Strength of the field. In the case of the gravitational field, you can see that there is roughly the same strength everywhere. One speaks here of a homogeneous field. In the case of bar magnets or magnets in general, on the other hand, the field lines are unevenly distributed. So it's a inhomogeneous field in front.

Determination of the field lines

To determine the field lines, a suitable test specimen is placed in the field and observed how it behaves at different points in time. Then you connect the individual points to a line.

In order to determine the field lines of a gravitational field (e.g. the earth), one can simply drop an object - like a ball. One observes how it moves in a straight line. This straight line is then a gravitational field line.

With magnetic fields, a magnetized body floating on water can be positioned at the pole of a bar magnet[2]. It then moves on a certain path to the other pole. A similar sequence is also obtained with electric fields. These paths then correspond to the field lines.

Disadvantages of the model

Since the field lines are only a model, reality can only be represented in a simplified manner. This is how the direction is shown. But this happens in a plane, while the field actually exists in space. It also works between the imaginary field lines. In addition, one can see the relative strength within the field; Statements about the absolute strength of the field are not possible[3].


  1. Fösel, Angela / Reinhard, Bernd / Sander, Peter / Schweitzer, Stefan / Thanner, Anton: Focus on Physics 9 - Bavarian High School, 12007 Berlin, Cornelsen Verlag, ISBN 978-3-464-85317-7.
  2. Gau, Barbara / Meyer, Lothar / Ried, Claudia and others: Physics 9 - Bavarian High School, 12007 Berlin, Paetec Schulbuch Verlag / C. C. Buchners Verlag, ISBN 978-3-8355-3059-1.


  1., Geek 3
  2. P. 10, focus on physics 9
  3. P. 11, physics 9