Force on a Point Charge: Finding the Location of a Third Charge

In summary, two particles with charges q and -2q are placed as shown in the figure. A third charge Q is placed on the x-axis and it is found that the total electric force on Q is zero. Using Coulomb's Law, it can be determined that Q is located in a region where the forces from the other two charges cancel out. The specific value of q or -2q does not affect the location of Q.
  • #1
acherentia
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Homework Statement



2 particles of charge q and -2q are located as shown in http://s966.photobucket.com/albums/ae146/acherentia/ . A third charge Q is placed on the x-axis and it is found that the total electric force on Q is zero. In which region of the figure is Q located?

Homework Equations



Coulomb's Law

The Attempt at a Solution



F1 + F2 = 0

F1(q on Q) = ?

F2(-2q on Q) = ?

What exactly does it mean a charge of -2q? Is it the same as the charge of 2 electrons?
 
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  • #2
Hi acherentia! :smile:
acherentia said:
What exactly does it mean a charge of -2q? Is it the same as the charge of 2 electrons?

It just means that the second charge is minus twice the first charge …

it could be one proton and two electrons, or just one coulomb of positive charge and two coulombs of negative charge, or any such combination. :wink:
 

FAQ: Force on a Point Charge: Finding the Location of a Third Charge

What is the formula for calculating the force on a point charge?

The formula for calculating the force on a point charge is F = k * (q1 * q2) / r^2, where F represents the force, k is the Coulomb's constant (9 x 10^9 Nm^2/C^2), q1 and q2 are the magnitudes of the charges, and r is the distance between the charges.

How is the direction of the force determined for a point charge?

The direction of the force on a point charge is determined by the relative position of the charges. If the charges are of the same sign, the force will be repulsive and if the charges are of opposite signs, the force will be attractive.

What is the relationship between the force on a point charge and the distance between two charges?

The force on a point charge is inversely proportional to the distance between two charges. This means that as the distance between the charges increases, the force decreases and vice versa.

Can the force on a point charge be negative?

Yes, the force on a point charge can be negative. This occurs when the charges are of opposite signs, resulting in an attractive force.

How does the presence of other charges affect the force on a point charge?

The presence of other charges can affect the force on a point charge through the principle of superposition. This means that the total force on a point charge is the vector sum of the forces from all the other charges present. In other words, the presence of other charges can alter the magnitude and direction of the force on a point charge.

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