Question

can an electric field exist at a point where the electrical potential there is zero

Answer 1

@ybarrap

Answer 2

A collection of points all at the same potential cannot be distributed throughout a volume. They must lie on a single surface
A.True
B.False

Answer 3

what about this question

Answer 4

the one question is false

Answer 5

the first one is yes an electric field can exist, as E = Grad of V so, even if V(x,y,z) = 0
the Grad of V at that point doesnt have to be zero

Answer 6

An electric field can exist and can be non zero where an electric potential is zero. The electric potential is the amount of work it takes to assemble the charges per unit charge at a particular location. The electric field is the force on that charge per unit charge. Therefore, just because you have done zero work to assemble charges, does not mean that the force on that charge at that point will also be zero.

Answer 7

i see, its hard to think of assembling a configuration with zero work, unless you are only moving 1 charge into empty space

Answer 8

OH I see what you are saying, i thought if there is no potential there is no, tendency for a charge to move there though, is that false

Answer 9

If you have a +2 charge sitting in front of a -1 charge and you are an electron and go infinity, those charges look like a +1 charge. That charge will attract you and you will be doing negative work. As you get closer to the -1 charge, you will then start to do positive work. At some point you transition from doing negative work to doing positive work. By the IVT, there is some point where the work is zero.

Answer 10

You are correct. There can still be an electric field acting on the charge even if he potential is zero.

Answer 11

ok its just werid to thin about because

Answer 12

For your second question, this would be true for a conducting surface. But for a nonconducting surface, the statement would be false. Since the question is generalized and does not specify why type of material, it is false.

Answer 13

for gravity, when someone is on the group, their potential = 0

Answer 14

there is a force acting on them, but there is no movement

Answer 15

but if you leave an electron in a potential on 0 in our case, it will indeed move, since there could be a force acting on it,

Answer 16

yes

Answer 17

i guess if the electron was being blocked by the floor too, then its the same deal as us

Answer 18

thanks u cleared some major confusion

Answer 19

look at this question,

Answer 20

For gravity, there is a point, say between the earth and the moon where the amount of work required to get you there is zero. But that does not mean that the gravitational field is zero. That's a good analogy.

Answer 21

yes true that makes sense

Answer 22

there is also an gfield that is zero, but then the work to get there is not zero

Answer 23

but once you do all the work to get there u can relax :)

Answer 24

for that diagram above i am thinking
dipole term only maters for large radius, so these charges would seem as a point charge and only the net charge would matter right

Answer 25

also the dipole term is smaller for quadroples and dipoles than monopoles

Answer 26

so maybe its E?

Answer 27

i thought it was B and D at first but thats wrong

Answer 28

I'm not a master of dipoles. I know few facts about them, for +q -q that they fall off as 1/r^3, for example (I know that). When you are far away, you can sum all the charges and they look like the sum of all those point charges. But their electric fields can be quite complex. I couldn't provide a good guess even.

Answer 29

alright
not to worry our prof will probably go over these questions on thursday

Answer 30

I'd be interested to know if there was a simple explanation if you can follow up if you remember, if not , no biggie.

Answer 31

i have a note on it u want to see?

Answer 32

sure

Answer 33

page 38 onwards he derives some dipole electric fields and potentials

Answer 34

Nice. Thanks!