Conducting Plates, electrical fields w/ conductor.

In summary, two plates are placed a distance "D" apart, with one plate charged +Q and the other -Q. An uncharged slab of metal is placed between the plates. The slab acts as a conductor with zero net electrical force, meaning it is neutral. This does not change the electric field outside or between the plates, but it does affect the forces exerted on particles between the plates. When a voltage is applied to the plates, the voltage on each side of the slab is the same and there is no electric field inside the slab. However, as the gap between the slab and the plates decreases, the electric field increases.
  • #1
lemurballs
3
0
1.Two plates placed a distance "D" apart. One charged +Q, the other -Q. An uncharged slab of metal is placed between the plates.



2. Does this slab change the electric field outside or between the plates (but outside the slab)? Do forces exerted on particle sitting between the plates (but outside the slab) change in any way with the slab as compared to before it was placed between the plates?



3. The slab acts as a conductor with zero net electrical force. I have no clue about the rest? Does the E-field increase between the plates because of the slab?

BONUS...same situation as in (1), but the plates are discharged, and a battery is hooked up with voltage V. An uncharged slab is again placed between the plates. Describe the e-field inside the metal slab... :eek:

:mad::mad::mad::mad::mad::uhh::uhh::uhh::frown::frown:
 
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  • #2
What do we know about capacitors:
Charge is conserved - so we can't change the Q on the plates.
There is no field inside a conductor ( assume the metal slab is a conductor!)
The voltage on each side of the slab is the same.
A conducting slab doesn't act like a dielectric

What is the field exactly half way between the plates? Now imaging a very thin slab placed here, what is the field on each side of the slab.
If the slab is thicker and fills more of the gap, the voltage on each side of the slab is still the same and the voltage on the plates is the same, what happens to the field as the gap betwen the slab and the plates gets smaller?
 
  • #3
If voltage stays the same and the gaps get smaller, the field has to get larger.

V=ED
 
  • #4
mgb_phys said:
There is no field inside a conductor ( assume the metal slab is a conductor!)

This is true ONLY if the particles inside the conductor are in static equilibrium.
 
  • #5
heafnerj said:
This is true ONLY if the particles inside the conductor are in static equilibrium.

it is GIVEN in the problem that: the e-field inside the metal slab is zero.
 
  • #6
Sounds right to me, an ungrounded uncharged conductor between the plates of a capacitor shouldn't have any other effect except to make the gap effectively smaller.
 
  • #7
lemurballs said:
it is GIVEN in the problem that: the e-field inside the metal slab is zero.

I'm afraid it is NOT given in the problem statement, which is strangely worded as you indicated in the original post. The statement

"The slab acts as a conductor with zero net electrical force."

is utter nonsense. A conductor, as a single entity, cannot possesses force.

A more concrete thing to say would something about the net charge on the slab. The intent is probably for the metal slab to be neutral. Now, what does THAT imply will happen when the slab is introduced between the capacitor's plates?
 
  • #8
heafnerj said:
"The slab acts as a conductor with zero net electrical force."
is utter nonsense. A conductor, as a single entity, cannot possesses force.
I assumed this meant the slab had no potential. Voltage translates as electric force (as in EMF) in a lot of languages.
 

1. What is a conducting plate?

A conducting plate is a flat surface made of a material that allows the flow of electric charges, such as metal. It is used to create and manipulate electrical fields in various applications.

2. How do conducting plates affect electrical fields?

Conducting plates influence electrical fields by providing a surface for the electric charges to accumulate and create an electric field. The shape and placement of the plates can also alter the strength and direction of the field.

3. Can conducting plates be used to shield from electric fields?

Yes, conducting plates can be used to shield from electric fields. When a conducting plate is placed between a source of electric field and an object, it can block or redirect the field, providing protection for the object behind it.

4. What is the role of a conductor in relation to conducting plates?

A conductor is a material that allows the flow of electric charges. Conducting plates are typically made of conductors and are used to manipulate and control electric fields due to their ability to accumulate charges and influence the direction and strength of the field.

5. How are conducting plates used in practical applications?

Conducting plates have various practical applications, including in electrical circuits, capacitors, and electromagnetic shielding. They can also be used in devices such as antennas, sensors, and touch screens, where they aid in the manipulation and control of electric fields.

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