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# What is an equipotential? watch

1. Just been revising phy5 and realised i have no definition of it.

I know that equipotentials are 90 degrees to field lines and get further away [i think by an inverse square law].

Im guessing that equi= equivalent/equal , potential = potential difference

so an equipotential is areas of the field lines where the potential difference is the same. Is this true?
2. An equipotential line is drawn from points which all have the same potential, eg. with gravitational fields, the points which all have the same gravitational potential form the equipotential line
3. do equipotentials exist on electric fields? I thought equipotentials existed on all 3 types of fields:

gravitation
electric
magnetic
4. yeah you can, and Ive just realised the defnition should be "line drawn from points with equal gravitational field strength" IU think, so for an electric field it will be points with the same values of electric firld strength, and with magnetic, same with magnetic field strength.
5. (Original post by nas7232)
do equipotentials exist on electric fields? I thought equipotentials existed on all 3 types of fields:

gravitation
electric
magnetic
yep they do.

An equipotential line is a line of equal enery per unit charge ofr an electric field and and equal enery per unit mass for a gravitational field.

it is perpendicular to the field lines in a uniform electric field eg between two parallel plate or a capacitor. you can use all the formulae for electical field strength with capacitors because they are analogous(similar).

hope it helps.

You can ask me any question on phy5, im quite good at that even tho i still need to do some rev, lol
6. 'I know that equipotentials are 90 degrees to field lines and get further away [i think by an inverse square law.'

Could you explain what that means...

Because i thought a uniform electric field had eqipotentials at equal intervals
8. I haven't really started fully on that (Physics 5), are u guys all taking Physics 4 too? will appreciate it if any one could graph a good way to revise for that, physics 4.
9. (Original post by Revenged)
'I know that equipotentials are 90 degrees to field lines and get further away [i think by an inverse square law.'

Could you explain what that means...

Because i thought a uniform electric field had eqipotentials at equal intervals
yeah, a uniform electric field has equipotentials at equal intervals (E = -dV/dx) (for two parallel plates for example), but (like for a sphere), it is not uniform and varies by an inverse square law (E proportional to 1/r²)
10. E = kQ/r^2 (k is a constant)

So when distance from the conducting sphere doubles the electric potential falls by a factor of 4?

So if you where drawing equipotential lines would the distance between the lines double each time you where going away from the sphere...
11. (Original post by Revenged)
E = kQ/r^2 (k is a constant)

So when distance from the conducting sphere doubles the electric potential falls by a factor of 4?

So if you where drawing equipotential lines would the distance between the lines double each time you where going away from the sphere...
yes, but it is unlikely they would ask us to draw it for a sphere.
12. if it's a radial feild, the inverse square law is applicable(farther the weaker), but does this apply to those in a parrellel plate?
13. (Original post by mikeA1)
if it's a radial feild, the inverse square law is applicable(farther the weaker), but does this apply to those in a parrellel plate?
for parallel plates, it does not apply (unless if there was a 'kink' in one of the plates, in which case the equipotentials would be closer at the point). But for parallel plates, it follows: E = -dV/dx.
14. (Original post by Revenged)
'I know that equipotentials are 90 degrees to field lines and get further away [i think by an inverse square law.'

Could you explain what that means...

yep, for a radial field => like a point charge or mass they graviationl field follows an inverse square law. this means that the equipotential lines will spread out with increasing distance from the point mass or charge.

Because i thought a uniform electric field had eqipotentials at equal intervals
for a unifor electriv field the equipotential lines have equal intervals because the field is constant within that region.
15. (Original post by Revenged)
E = kQ/r^2 (k is a constant)

So when distance from the conducting sphere doubles the electric potential falls by a factor of 4?

So if you where drawing equipotential lines would the distance between the lines double each time you where going away from the sphere...
formula wrong..

its EP = kQ/r
16. it's not applicable for a uniform field, it's just at 90 degrees. Above i was talking about a radial field.
17. (Original post by ARCHK0VEN)
formula wrong..

its EP = kQ/r
Nope it's an inverse square law

V = kQ/r
18. (Original post by ARCHK0VEN)
formula wrong..

its EP = kQ/r
no, he is talking about electric field strength and not electric potential
19. (Original post by nas7232)
it's not applicable for a uniform field, it's just at 90 degrees. Above i was talking about a radial field.
yep, for a radial field => like a point charge or mass they graviationl field follows an inverse square law. this means that the equipotential lines will spread out with increasing distance from the point mass or charge.
20. isit clear now?

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