scientific222
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Could someone explain to me what is happening in this question? Why are the field lines going from the positive V plates to the 0V plate. If this is the case, does a higher voltage not lead to a strong electric field strength, why are the electric field strength lines the same from both plates(600V and 1200V) going to the 0V?

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uberteknik
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(Original post by scientific222)
Could someone explain to me what is happening in this question? Why are the field lines going from the positive V plates to the 0V plate. If this is the case, does a higher voltage not lead to a strong electric field strength, why are the electric field strength lines the same from both plates(600V and 1200V) going to the 0V?

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Electric fields are defined by a convention and always from the more +ve potential to the more -ve potential. An electric field is a description of the electrostatic force a charged particle will experience at any point in 3d space within the vicinity of other charged particles.

The plates have an accumulation of charge on them and this is represented by the voltage depicting the potential energy of that charge as a Voltage (Joules per coulomb of charge).

In this question 0V is more -ve than both +600V and +1200V and hence the direction of the field lines.

The parallel spacing of the field lines is not an indication of field strength at any given point. They are a representation that the field strength is the same at all points on any line parallel with the plates and the grid.
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scientific222
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(Original post by uberteknik)
Electric fields are defined by a convention and always from the more +ve potential to the more -ve potential. An electric field is a description of the electrostatic force a charged particle will experience at any point in 3d space within the vicinity of other charged particles.

The plates have an accumulation of charge on them and this is represented by the voltage depicting the potential energy of that charge as a Voltage (Joules per coulomb of charge).

In this question 0V is more -ve than both +600V and +1200V and hence the direction of the field lines.

The parallel spacing of the field lines is not an indication of field strength at any given point. They are a representation that the field strength is the same at all points on any line parallel with the plates and the grid.
Thanks. However I am still confused about the last part. My book says that the spacing of the field lines indicates the strength of the electric field. But you are saying the spacing is not an indication of field strength. In this diagram is it not true that if you put a +ve charge close to the 600V and the same +ve charge close to the 1200V, the electric field strength is different at both those points?
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krisshP
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E=V/d
E=p.d. Across plates / plates separation

That tells us the electric field strength.
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uberteknik
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(Original post by scientific222)
Thanks. However I am still confused about the last part. My book says that the spacing of the field lines indicates the strength of the electric field.
That is true, but in this it is overriden by the statement at the bottom of the page which reads:

"Field lines equally spaced to show uniform field".

Uniformity and strength are not the same thing.

Think about it:

The force on any given particle is given by Coulombs law F = kQ1Q2/d2

If the separation of the field lines indicates field strength (the lines must diverge as they recede from the plates), they cannot then indicate a uniform field at all places (parallel lines) and vice versa.
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(Original post by scientific222)
Thanks. However I am still confused about the last part. My book says that the spacing of the field lines indicates the strength of the electric field.
Normally that would be true. However the statement at the bottom of the page overrides it in this particular case by saying "Field lines equally spaced to show uniform field"

(Original post by scientific222)
In this diagram is it not true that if you put a +ve charge close to the 600V and the same +ve charge close to the 1200V, the electric field strength is different at both those points?
Yes it is true. However, the example is trying to depict uniformity of the field as a concept and not a representation of the relative field strength between the plates and grid.
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