I don't really understand Coulombs Law

[bran91bran]

1. How much Coulombs force is exerted on a proton by an electron if they are 15mm away from each other? Is the force attractive or repulsive?



2. http://www.glenbrook.k12.il.us/gbssci/phys/Class/estatics/u8l3b1.gif where k=9* 10^9 N*m^2/c^2



3. I know that the force is attractive,http://www.glenbrook.k12.il.us/gbssci/phys/Class/estatics/u8l3b2.gif but I don't know where to find some elements in Coulombs law.

 

[LowlyPion]

Welcome to PF.

Electron

Electric charge: −1.602176487(40)×10⁻¹⁹ C

Proton

Electric charge: 1.602176487(40)×10⁻¹⁹ C

 

[nlightner]

I can understand your confusion with Coulomb's Law. It is a fundamental law in electrostatics that describes the force between two charged particles. In order to better understand this law, let's break it down into its components.

1. Coulomb's Law states that the force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. In mathematical terms, it can be written as F = k * (q1 * q2)/r^2, where F is the force, k is the Coulomb's constant (9 * 10^9 N*m^2/c^2), q1 and q2 are the charges of the two particles, and r is the distance between them.

To answer your first question, we can plug in the given values into the equation. Since we are dealing with a proton and an electron, we know that q1 = 1.6 * 10^-19 C (charge of a proton) and q2 = -1.6 * 10^-19 C (charge of an electron). The distance between them is 15mm, which is equivalent to 0.015m. Plugging these values into the equation, we get F = (9 * 10^9 N*m^2/c^2) * (1.6 * 10^-19 C * -1.6 * 10^-19 C)/(0.015m)^2. This gives us a force of approximately 2.56 * 10^-28 N.

2. The value of k in Coulomb's Law is a constant that represents the proportionality between the force and the other variables in the equation. It is derived from other fundamental constants, such as the permittivity of free space and the speed of light. Its value is approximately 9 * 10^9 N*m^2/c^2.

3. From the equation, we can see that the force between two charged particles is always attractive if the charges are of opposite sign (one positive and one negative) and repulsive if the charges are of the same sign (both positive or both negative). This is because the product of the two charges will be either positive or negative, but the inverse square of the distance will always be positive. So, in your example, the force between the proton and electron is attractive because they have opposite charges.

I hope this