Voltage between Plates vs. Distance

[sexycani]

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If you increase the distance between two plates do you increase or decrease the voltage?

I am a little confused because of the conflicting equations:

V = Ed
while E = kQ/d

i cant figure out if the voltage increases or decreases with increasing distance between plates

 

[Rabolisk]

Depends on what you are holding constant.

 

[sexycani]

lets say you are holding charge constant

but wouldn't separating the plates still affect the electric field inversely while directly affecting the Voltage? how do you make sense of this apparent contradiction?

 

[flodhi1]

If you increase the distance between two plates do you increase or decrease the voltage?

I am a little confused because of the conflicting equations:

V = Ed
while E = kQ/d

i cant figure out if the voltage increases or decreases with increasing distance between plates

Okay so Electric field is = kq1/r^2 and Voltage = kr1/r thus to MATHEMATICALLY using algebra convert Electric field (E) to Voltage you would multiply distance (r) to it. Regardless that has nothing to do with it what you need to pay attention is to the intuitive sense of the problem not just memorizing a formula and using it. If you are using a CHARGE and the distance between the charge increases than Voltage will decrease. However if you have SET the electric field CONSTANT and you increase the distance you will increase the Electric field. This formula is of V=Ed is not to be taken literally as V = kq/r should be taken. Since V=Ed is just a mathetical relationship based on Electric field and voltage. It all comes down to the situation you are given. These formulas DO NOT contradict eachother because in this situation r and d are used for correlating E and V

 

[Rabolisk]

Separating the plates does not actually lower the electric field between them. This is because kQ/r^2 does not apply to capacitor plates. Under the assumption that the distance we are talking about is small compared to the area of the plates, increasing the distance between the plates while holding charge constant increases voltage, lowers the capacitance, and has no effect on the electric field. This can be proven using Gauss's Law. On the other hand, if you increase the distance enough so that the separation between the plates is much greater than the area of the plates, then you can simply the plates to just be point charges, and kQ/r^2 would be valid. The key point here is that capacitors (two plates of equal charge separated by a small distance) cannot be treated mathematically as same as two point charges.