Where the electric field is zero

In summary, the net electric field between two fixed charges of -20.6 microC and +4.2 microC is zero at a spot 2.71679m from the positive charge. The magnitude of the force on a third charge of +24.1 microC placed at this spot would be 0.123286 N. The force between the +24.1 microC and +4.2 microC charges would be equal and opposite to this force, making it 0 N.
  • #1
JJones_86
72
0

Homework Statement


Two charges, -20.6 microC and +4.2 microC, are fixed in place and separated by 3.3 m.

(a) At what spot along a line through the charges is the net electric field zero? Locate this spot relative to the position of the positive charge.

(b) What would be the magnitude of the force on a third charge +24.1 microC placed at this spot?


Homework Equations



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

The Attempt at a Solution



None

-----------------

I've got part A to be 2.71679m from the positive charge, I just don't know how to do part B. The equation I posted seems to me irrelevant because there are now 3 charges. Any help is appreciated.
 
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  • #2
(b) What would be the magnitude of the force on a third charge +24.1 microC placed at this spot?
Find the force between +24.1 microC and+ 4.2 micro C. Force due to other charge will be equal and opposite to this force.
 
  • #3
rl.bhat said:
(b) What would be the magnitude of the force on a third charge +24.1 microC placed at this spot?
Find the force between +24.1 microC and+ 4.2 micro C. Force due to other charge will be equal and opposite to this force.

F = k*q1*q2/r^2
F = 8.99E9(4.2E-6)(24.1E-6)/2.71679^2
F = 0.123286 N?
 
  • #4
rl.bhat said:
(b) What would be the magnitude of the force on a third charge +24.1 microC placed at this spot?
Find the force between +24.1 microC and+ 4.2 micro C. Force due to other charge will be equal and opposite to this force.

I'm not exactly sure what you mean by equal and opposite, would it make it 0 N then?
 

1. What is the electric field?

The electric field is a force field that exists around charged particles, such as electrons and protons. It is a vector quantity, meaning it has both magnitude and direction.

2. Where can the electric field be zero?

The electric field can be zero at various points in space, depending on the distribution of charges. For example, if two equal and opposite charges are placed close to each other, the electric field between them will be zero at the midpoint between the charges.

3. How can I find where the electric field is zero?

To find where the electric field is zero, you can use the electric field equation: E = kq/r^2, where k is the Coulomb's constant, q is the charge, and r is the distance from the charge. Set the equation equal to zero and solve for r to find the distance from the charge where the electric field is zero.

4. Can the electric field be zero at more than one point?

Yes, the electric field can be zero at multiple points in space. This can occur when there are multiple charges present in a specific configuration, such as a line of charges or a ring of charges.

5. Why is it important to know where the electric field is zero?

Knowing where the electric field is zero can help in understanding the behavior of charged particles and the interactions between them. It is also important in practical applications, such as designing circuits and determining the stability of atomic structures.

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