Electric Force/ Electrical Fields

In summary, an electron released above Earth's surface experiences an electrostatic force from a second electron directly below it, cancelling out the gravitational force. The distance between the two electrons can be solved for using the equation F= Ke (q1)(q2)/r^2, where q1 and q2 are the charges of the electrons and r is the distance between them. This equation can be used even without specific numerical values, as long as the mass and charge of an electron are known. The value of 8.85x10^-12 can be used for the permittivity of free space, represented by the symbol E0. Using this equation, the distance between the two electrons can be calculated to be approximately 4
  • #1
xswtxoj
87
0

Homework Statement



An electron is released a short distance above Earth's surface. A 2ndelectron directly below it excerts an electrostatic force on the 1st electron just great enough to cancel the gravitational force on it How far below the 1st electron is the 2nd?

Homework Equations



F= Ke (q1)(q2)/r^2

The Attempt at a Solution

 
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  • #2
Since the two forces are acting in opposite directions and you want them to add to zero you can set your gravity force equation equal to the electric force equation. Then you should be able to solve for the distance "r".
 
  • #3
Can you write it out for me? I don't quite understand what you mean!
 
  • #4
Well the force of gravity on the 1st electron is can be found using [itex] F=ma [/itex] where "a" = g = acceleration due to gravity 9.8 [itex] \frac{m}{s^2} [/itex]. You already have the equation for the force between the two electrons due to their charge. Since you want the forces to be equal(becuase they are opposing and cancel each other out) you can set both of these equations equal to each other. Then the only variable you won't know in this combined equation should be r which is the distance between the paritcles' centers. Your equation should look something like

[tex]
mg = \frac{q_1 q_2}{4 \pi \epsilon_0 r^2}
[/tex]
 
  • #5
how would u solve this problem if no numbers are given? i really don't get this?
 
  • #6
what u said so i set up the equation and to cancel is like Keqq= Frsq then qq=mg4 pi Eo rsq, then cancel all like terms, to have Ke=F=mg4 pi Eo?
 
  • #7
xswtxoj said:
how would u solve this problem if no numbers are given? i really don't get this?

It's an electron.

You are expected to look it up.

http://en.wikipedia.org/wiki/Electron
 
  • #8
considering that its an electron as 1.6 x 10^-19, and ur finding the distances, how would u apply that to the 2 equations above?
 
  • #9
xswtxoj said:
considering that its an electron as 1.6 x 10^-19, and ur finding the distances, how would u apply that to the 2 equations above?

DukeLuke gave you the equation. So look up the mass.

Solve for R.
 
  • #10
can the equation be used as q1q2/ 4 pi (8.85x 10 ^-12 ) r sq,,,, the 8.85 be used for E0?
 
  • #11
xswtxoj said:
can the equation be used as q1q2/ 4 pi (8.85x 10 ^-12 ) r sq,,,, the 8.85 be used for E0?

Yes. Of course.
 
  • #12
is i use the [tex]mg = \frac{q_1 q_2}{4 \pi \epsilon_0 r^2}[/tex] then would it be: 9.8= 1.6 E -19 sq/ 4 (3.14)(8.85 E -12) r2, then cross multiply to get 9.8 x 4 x 3.14 x 8.85xE-12 (r sq) = 1.6x10-19 sq then get 1.089E -9 (r sq) = 2.56x -38 then divide to isolate r sq, then solve for r to get 4.84E -15
 

Related to Electric Force/ Electrical Fields

1. What is an electric force?

An electric force is a fundamental force of nature that is responsible for the attraction or repulsion between electrically charged particles, such as protons and electrons. It is caused by the interaction of electric fields.

2. How is electric force different from other forces?

Electric force is unique because it can act over long distances, unlike other fundamental forces such as gravity or the strong and weak nuclear forces, which have a limited range.

3. What is an electrical field?

An electrical field is a physical field that surrounds an electrically charged particle or group of particles. It describes the strength and direction of the force that a charged particle would experience if placed at any given point in the field.

4. How is an electrical field created?

An electrical field is created by any object that has a net electric charge. The field is strongest near the charged object and decreases in strength as you move further away.

5. What are some real-world applications of electric force and electrical fields?

Electric force and electrical fields have many practical applications in our daily lives. They are essential for generating electricity, powering electronic devices, and controlling the flow of electricity in circuits. They are also important in technologies such as telecommunication, medical equipment, and transportation systems.

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