Electric field lines between 20/30 V point charges vs. 10/0 V

[miaou5]

Homework Statement

What would the electric field lines / equipotential lines look like between point charges that are set up with potentials of 20 volts and 30 volts versus point charges that are set up with potentials of 0 volts and 10 volts?

The Attempt at a Solution

At first I thought the electric field lines would look different, but the more I thought about it, the more it seemed like they would be the same, since only the difference in V counts as opposed to the "absolute" values of V. Is this correct? Thank you all so much!

Added question: I completely forgot about this, but would the lines extend from the 10 V charge toward the 0 V? I know the lines go from the positive charge from the negative charge, so I'm pretty sure they would go from the higher V to the lower V, but I just wanted to make sure. Thank you!

 

[BruceW]

It is true that only difference of voltage is important but remember the convention about voltage at infinitely far away. This is important for this problem.

 

[miaou5]

Thank you so much!

 

[BruceW]

hehe. no problem!

 

[willem2]

What is a point charge set up with a potential of 20 V ?

Since the potential due to a point charge is

[tex] \frac {1}{4 \pi \epsilon_0} \frac {Q}{r} [/tex]

the potential near a point charge will become infinite for any non-zero charge.
If the point charge is merely a very small sphere, you still need to know the radius to get the charge from the potential.