# Electric field lines between a point-charge and a conducting sheet

• huszarerik
In summary, an electric field line is an imaginary line that represents the direction and strength of an electric field. It is drawn by determining the direction at various points and drawing lines perpendicular to the surface of a conducting sheet, with the density indicating the strength. These lines do not intersect as it would mean two different field directions and strengths. The spacing of the lines indicates the strength of the electric field, with closer spacing indicating a stronger field. If the distance between a point charge and a conducting sheet is increased, the electric field lines become more spread out, indicating a weaker field due to the decrease in field strength with distance.
huszarerik
Homework Statement
In the electric field of the point-charge (Q) above the conducting sheet (fig 1), we follow an electric field line, which leaves the point-charge parallel to the sheet. Where will the electric field line meet the surface of the conducting sheet?
Relevant Equations
Gauss's Law: ∫ E⋅da=Qin/ε
Charge density on the conductor: σ=-Q*h/2*π*(r^2+h^2)^(3/2)
where:
h = distance from the point-charge to the sheet
r = distance along the horizontal axis on the conducting sheet
figure 1: →

I don't understand how to approach this problem. Basically it asks for the distance r.I think I should use Gauss's law, but I've been thinking about the shape of the gaussian surface and I'm not sure about how it should look or where I should place it. Any help would be useful, especially in terms of ideas.
Thank you.

Last edited:
I would use the mirror trick and consider the total flux through a disc of given radius centred between the two opposite charges.

## 1. What is an electric field line?

An electric field line is a visual representation of the direction and strength of an electric field. It is drawn as a continuous line where the tangent at any point represents the direction of the electric field.

## 2. How are electric field lines between a point-charge and a conducting sheet formed?

Electric field lines between a point-charge and a conducting sheet are formed due to the interaction between the two charged objects. The point-charge creates an electric field, and the conducting sheet acts as a boundary, causing the electric field lines to bend and terminate at the sheet.

## 3. What do the electric field lines tell us about the electric field between a point-charge and a conducting sheet?

The electric field lines provide information about the strength and direction of the electric field between the two charged objects. The closer the lines are to each other, the stronger the electric field, and the direction of the lines indicates the direction of the electric field.

## 4. Can the electric field lines between a point-charge and a conducting sheet intersect?

No, the electric field lines cannot intersect because they represent the direction of the electric field at each point. If they were to intersect, it would mean that the electric field has two different directions at the same point, which is not possible.

## 5. How can we use electric field lines to calculate the electric field strength between a point-charge and a conducting sheet?

The electric field strength can be calculated by measuring the distance between the electric field lines. The closer the lines are to each other, the stronger the electric field. Additionally, the number of lines per unit area can also be used to determine the strength of the electric field.

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