Two Electric Charges- Electric Force-Ranking

In summary, the conversation discusses seven arrangements of two electric charges, all of which are the same size (20 C) but have different polarities. Each arrangement also includes a point labeled P, which lies on a straight line with the two charges and is 5 cm away from them. A +5 C charge is placed at point P and the task is to rank the strength of the electric force on this charge from greatest to least. The equation Fe= k(q1q2)/r^2 is relevant for determining the strength of the electric force. After discussing the distances between the charges and the direction of the forces, the conversation concludes with the understanding that the charges in each arrangement have equal magnitudes and the direction of the forces depends
  • #1
jeandempsey
6
0

Homework Statement


Below are seven arrangements of two electric charges. All of the charges are the same size, 20 C, but they are either positive or negative. Each figure also has a point labeled P that lies on a straight line with the two charges. The distance between any two items is all 5 cm. There are no other charges in this region. A +5 C charge is placed at point P. Rank the strength (magnitude only) of the electric force on the +5 C charge when it is placed at point P from greatest to least.

Screenshot2011-12-03at23621AM.png


Homework Equations


Fe= k(q1q2)/r^2

The Attempt at a Solution


help get me started please? :) I don't know how to get started.
 
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  • #2
jeandempsey said:
The distance between any two items is all 5 cm.

What do you mean by that? Is 5 cm the distance from P of both the + and - charges?

ehild
 
  • #3
between any two items is 5 cm. For example, in C,
between - and P it is 5 cm and between P and + it is 5 cm.
 
  • #4
And what is the distance between + and - in B?
Anyway, the + and - charges are of the same in magnitude, so what about the force they exert on the charge at P if the distances are equal? What about the direction the forces? Draw the forces with arrows in the pictures, and determine the resultant.

ehild
 
  • #5
Oh! I think I understand it now. Thank you
 
  • #6
jeandempsey said:
Oh! I think I understand it now. Thank you
Hi jeandempsey. Welcome to PF.

Would you like to give your answers & your reasoning so that ehild or one of our other homework helpers can check that you really do understand this.
 

1. What is the electric force between two charges?

The electric force between two charges is given by Coulomb's law, which states that the force is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them. It is also dependent on the medium between the charges and is a vector quantity, meaning it has both magnitude and direction.

2. How do you calculate the electric force between two charges?

To calculate the electric force between two charges, you can use Coulomb's law, which is F = k(q1q2)/r2, where F is the electric force, k is the Coulomb's constant, q1 and q2 are the charges, and r is the distance between them. The direction of the force can be determined using the principle of like charges repelling and opposite charges attracting.

3. What is the unit of electric force?

The unit of electric force is Newtons (N) in the SI system. In the CGS system, the unit is dynes (dyn). Both units are equivalent to kg*m/s2 and are used to measure the strength of the force between two charges.

4. Can the electric force between two charges be negative?

Yes, the electric force between two charges can be negative. This occurs when the two charges are of opposite signs (one positive and one negative), and the force is attractive. The negative sign indicates that the force is acting in the opposite direction of the positive charge.

5. How does the distance between two charges affect the electric force between them?

The distance between two charges has an inverse-square relationship with the electric force between them. This means that as the distance increases, the force decreases, and vice versa. So, the force is stronger when the charges are closer and weaker when they are farther apart. This relationship is described by Coulomb's law, which states that the force is inversely proportional to the square of the distance between the charges.

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