Is Electrostatic Potential Zero When Electric Field Is Zero?

In summary, we discussed various topics related to electric and gravitational fields. We learned that if the electric field is zero in a region, it does not necessarily mean that the potential is also zero, and an example of this is given by a conductor that is not in equipotential. We also discussed the safety precautions one should take if a high voltage cable falls on top of a car and how we can shield a region from external electric fields. Finally, we explored the idea of closed field lines and how it applies to electric and gravitational fields.
  • #1
burak_ilhan
14
0
1}If the electric field is zero in some region, must the potential also be zero?An example?

2}Give an example of a conductor that is not an equipotential.Is this conductor in electrostatic equilibrium?

3)If a high voltage cable falls on top of your automobile, will you probably be safest if you remain inside the automobile.Why?

4)If we surroun some region with a conducting surface, we shield it from external electric fields. Why can we not shield a region gravitational field by a similar method?

Its clear that these questions need no mathematical work,i'd like to discuss them with forum members
 
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  • #2
You gave the answer to 3 in 4.
 
  • #3
yes but a car is not compeletely closed with metal(windows).And what will happen if you open a door and try to get out?
 
  • #4
1) No, it just means that the potential isn't changing. Remember that potential is a totally relative quantity, anyway. You can define the potential relative to 0V or relative to 50,000,000V if it floats your boat.

2) Here's half of it: a conductor in an electrostatic arrangement will also be equipotential. There was actually a nice little discussion about it in a different thread, https://www.physicsforums.com/showthread.php?s=&threadid=15931&perpage=15&pagenumber=1

3) Oh yes. If that does happen, don't get out and don't touch the ground! Remember that your car is insulated from the ground by your tires (unless your exhaust or something is dragging , like my poor car is apt to do), so it's just going to hold all that charge. If you, a pretty nice conductor, decide to try to step out of the car, you're going to be a path for that charge the car is holding to travel through to the ground. I don't know about you, but I'd rather not be a make-shift powerline.

4) There's no negative mass like there is negative charge.

cookiemonster
 
  • #5
The car is not insulated from the ground by the tires because the electric field of the lightning bolt is strong enough to cause the air surrounding the car to undergo electrical breakdown. In other words the charge gets conducted through the air to the ground.
 
  • #6
the absence of electrostatic fields in closed conducting cavities is proved by using the idea that the electrostatic field as a conservative field:

[tex]0=\oint E.dl[/tex]

this equation implies that a field line can never form a closed loop.
In my opinion this cannot be applied to gravitational fields because gravitational field lines can form a closed loop.Is that correct?If it is anyone knows how to explain this mathematically?
 
  • #7
In my opinion this cannot be applied to gravitational fields because gravitational field lines can form a closed loop.Is that correct?If it is anyone knows how to explain this mathematically?

They can't. The line integral formula you wrote down means that a field is conservative, as you said. Well a grav. field definitely is!

My response to 2:
A conductor that is not in equipotential "contains" an el. field, the result is a current, so it isn't an electrostatic situation. An example for this is the cable that sends the signal to your screen right now. But as long as we have electrostatic equilibrium in a conductor, we have an equipotential.
 

FAQ: Is Electrostatic Potential Zero When Electric Field Is Zero?

What is electrostatic potential?

Electrostatic potential, also known as electric potential, is a measure of the amount of electrical potential energy that a charged particle has due to its position in an electric field.

How is electrostatic potential calculated?

Electrostatic potential is calculated by dividing the electric potential energy of a charged particle by its charge.

What is the unit of measurement for electrostatic potential?

The unit of measurement for electrostatic potential is volts (V).

How does distance affect electrostatic potential?

Distance has an inverse relationship with electrostatic potential - as distance increases, electrostatic potential decreases. This means that the further away a charged particle is from a source of electric field, the lower its electrostatic potential will be.

What is the practical application of electrostatic potential?

Electrostatic potential has many practical applications, including in electrical circuits, capacitors, and electronic devices. It is also important in understanding and predicting the behavior of atoms and molecules in chemistry and biology.

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