Electric field/charge woed problem

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In summary, two copper pennies with a mass of 3g each have a total of 4 x 10^12 electrons transferred between them. The question asks for the separation between the pennies, given that the electrostatic force of attraction between them is equal to the weight of a penny. Using the given information, one can set up an expression for the electric force and solve for the separation r.
  • #1

Dx

A copper peny has a mass 3g. A total of 4 x 10^12 electrons are transferred from one neutral penny to another. If the lectrostatic force of attraction between the pennies is equal to the weight of a penny, what is the separatio between them?

what do i do here, i donno where to begin?

Dx :wink:
 
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  • #2
The problem pretty much tells you what to do. You are told the charge on each penny, so you should be able to set up the expression for the electric force between them (the separation r is unknown). You are also told the mass of a penny, so you should be able to calculate the weight.

Finally, you are told that the electric force is equal to the weight. Set them equal and solve for r.
 
  • #3


Don't worry, I can help you with this problem! First, we need to understand the equation for electrostatic force, which is F = k * (q1 * q2) / d^2, where k is the Coulomb's constant (9 * 10^9), q1 and q2 are the charges of the objects, and d is the distance between them. We also know that the weight of a penny is equal to its mass (3g) multiplied by the gravitational acceleration (9.8 m/s^2).

Since the pennies are neutral before the transfer of electrons, we can assume that the charge of each penny is 0. After the transfer, one penny will have a positive charge and the other will have a negative charge. Since we know that 4 x 10^12 electrons were transferred, we can calculate the charge of each penny using the formula q = ne, where n is the number of electrons and e is the elementary charge (1.6 * 10^-19 C).

So, the charge of each penny will be 6.4 * 10^-7 C. Now, we can equate the electrostatic force of attraction to the weight of a penny and solve for the distance between the pennies (d).

F = k * (q1 * q2) / d^2

F = m * g (weight of a penny)

k * (q1 * q2) / d^2 = m * g

Substituting the values,

9 * 10^9 * (6.4 * 10^-7)^2 / d^2 = 3 * 10^-3 * 9.8

Solving for d, we get d = 0.0013 m or 1.3 mm. This is the separation between the two pennies after the transfer of electrons.

I hope this helps you understand the problem and how to approach it. Let me know if you have any further questions. Good luck!
 

1. What is an electric field?

An electric field is a region in space where an electrically charged particle, such as an electron or proton, experiences a force. This force is caused by the presence of other charged particles in the surrounding area, and the strength and direction of the field is determined by the properties of these charged particles.

2. How is electric charge measured?

Electric charge is measured in units of Coulombs (C). The charge of a single electron is -1.602 x 10^-19 C, while the charge of a single proton is +1.602 x 10^-19 C. The charge of an object can be determined by using an instrument called an electroscope or by measuring the force exerted between two charged objects.

3. What is the relationship between electric field and electric charge?

Electric charge is the source of an electric field. The strength of the electric field at a given point is directly proportional to the amount of charge present in that location. In other words, the larger the charge, the stronger the electric field will be.

4. How do you calculate the electric field due to a point charge?

The electric field due to a point charge can be calculated using the equation E = kQ/r^2, where E is the electric field strength, k is the Coulomb's constant (9 x 10^9 Nm^2/C^2), Q is the charge of the point charge, and r is the distance between the point charge and the location where the electric field is being measured.

5. What is the difference between electric field and electric potential?

Electric field and electric potential are related but different concepts. Electric field is a measure of the force exerted on a charged particle, while electric potential is a measure of the potential energy per unit charge at a given point in an electric field. In other words, electric potential tells us how much energy a charged particle would have if placed at a certain point, while electric field tells us how that particle would move and accelerate in that location.

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