A very large sheet of insulating material has had electrons removed from it to yield a surface charge density of +6.00 nC/m2.

(a)
As the distance from the sheet increases, does the potential increase or decrease?
increase
decrease
Correct: Your answer is correct.
Can you explain why without any calculations?
The electric field points in the direction of increasing potential while pointing towards negative charges and away from positive charges.
The electric field points in the direction of increasing potential while pointing away from negative charges and towards positive charges.
The electric field points in the direction of decreasing potential while pointing towards negative charges and away from positive charges.
The electric field points in the direction of decreasing potential while pointing away from negative charges and towards positive charges.
Correct: Your answer is correct.
Does the location of your reference point matter?
Yes
No
Correct: Your answer is correct.
(b)
What is the shape of the equipotential surfaces?
planes perpendicular to the sheet
spheres whose centers lie on the sheet
planes parallel to the sheet
spheres whose centers do not lie on the sheet
Correct: Your answer is correct.
(c)
What is the spacing (in m) between surfaces that differ by 9.50 V?

1 answer

To find the spacing between equipotential surfaces that differ by 9.50 V for a uniformly charged infinite sheet with a surface charge density of +6.00 nC/m², we can follow these steps:

  1. Determine the Electric Field (E): The electric field \( E \) created by an infinite sheet of charge can be calculated using the formula:

    \[ E = \frac{\sigma}{2\epsilon_0} \]

    where:

    • \( \sigma \) is the surface charge density (\(+6.00 , \text{nC/m}^2 = 6.00 \times 10^{-9} , \text{C/m}^2\)),
    • \( \epsilon_0 \) is the permittivity of free space (\(8.85 \times 10^{-12} , \text{C}^2/\text{N m}^2\)).

    Plugging in the numbers:

    \[ E = \frac{6.00 \times 10^{-9}}{2 \times 8.85 \times 10^{-12}} \approx 339 , \text{N/C} \]

    The factor of 2 accounts for the contribution of the field from both sides of the sheet. Notice that the direction of the electric field is away from the positively charged sheet.

  2. Relating Electric Field and Potential Difference: The relationship between the electric field and the potential difference \( V \) over a distance \( d \) is given by:

    \[ V = E \cdot d \]

    We need to rearrange this equation to find the distance \( d \):

    \[ d = \frac{V}{E} \]

  3. Calculate the distance for a 9.50 V potential difference:

    \[ d = \frac{9.50 , \text{V}}{339 , \text{N/C}} \approx 0.02796 , \text{m} \approx 0.028 , \text{m} = 28 , \text{mm} \]

Thus, the spacing between equipotential surfaces that differ by 9.50 V is approximately 0.028 m (or 28 mm).