5
$\begingroup$

We can see magnetic field lines by putting compasses or iron filings around a wire that carries current, is there a way to see electric field lines so we can see electric field lines just like we can see magnetic field lines when we put compasses or iron filings around a wire?

$\endgroup$

1 Answer 1

9
$\begingroup$

You can use, for example, grass seeds in oil.

See this video lecture, "Demo-by-Lewin(8.02-02-2): Display electric fields with grass seeds"

Update:

James Lincoln has some additional methods in these videos: “10 Ways to SEE the ELECTRIC FIELD ”part1 and part2.

$\endgroup$
12
  • $\begingroup$ Thank you, how about a single charge? Those in that video are two charges. $\endgroup$
    – SnoopyKid
    Commented Apr 29, 2023 at 13:26
  • $\begingroup$ @SnoopyKid You can try to isolate the single “point charge” by moving the other objects away… For example, use a large ring with the point inside. $\endgroup$
    – robphy
    Commented Apr 29, 2023 at 13:40
  • 1
    $\begingroup$ That's really cool. I wonder if it is possible to see both electric field lines and magnetic field lines around a wire or anything at the same time, or will one of them dominate the other so that only a single field will be observed? $\endgroup$
    – SnoopyKid
    Commented Apr 30, 2023 at 2:55
  • 1
    $\begingroup$ ...but the problem then is that you would now have to dissipate a lot of power ($P = I \times V$) to get both a strong electric and strong magnetic field, and that would probably induce big convection currents in the oil that would make your seeds start to move around. It sounds pretty difficult. I recommend you ask that as a new question post so you can make space for new answer posts. I think it would be a great new question! $\endgroup$
    – uhoh
    Commented Apr 30, 2023 at 5:02
  • 1
    $\begingroup$ @SnoopyKid The location of the spark on the object indicates that the electric field is strong enough there to "ionize the air" so that air is no longer an insulator, but a conducting fluid. The path of the spark in the air is guided by the electric field, but also includes a lot of randomness [like in a lightning strike]. So, while fascinating to look at, those are not reliable indicators of [just] the electric field. $\endgroup$
    – robphy
    Commented May 5, 2023 at 15:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.