How to Calculate and Measure Electrical Forces: Point Charges Problem 22

In summary, the conversation discusses a problem involving two positive point charges with a charge of 1.9*10^-9C each, located at y=0.38m and y=-0.38m. The question is to find the magnitude and direction of the resultant electrical force on a charge of 1.8*10^-9 C located at x=0.28m. The conversation includes a calculation using the formula a^2+b^2=c^2, but the answer was incorrect. It is suggested to use vector components or the sin law to find the correct answer. However, in this specific case, symmetry can be used to simplify the solution.
  • #1
mustang
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0
Problem 22.
Two positive point charges, each of which has a charge of 1.9*10^-9C, are located at y=0.38m and y=-0.38m.
a. Find the magnitude of the resultant electrial force on a charge of 1.8*10^-9 C located at x=0.28m. Answer in N.
Note: I used a^2+b^2=c^2 to find r in Coluomb's law which I got as 0.472016949. From that I added F_1+F_2 to get 0.0000000276N which was wrong, what did I do wrong?
b. What is the direction of this force(measured from the positive x-axis, with counterclockwise positive)? Answer in degrees.
Note: Would I find the angle by dividing the two electric force answers and times by tan-1?
 
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  • #2
No, you should, in general, use the fact that a vector, of length v, making angle θ with the x-axis has x-component v cosθ and y-component v sinθ then add the two vector component wise.
Another way is to use the sin law in the triangles formed.

Actually, in this case, the answer is very simple: since the charges are the same and are symmetrically placed, use symmetry.
 
  • #3
Answer

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What is a point charge?

A point charge is a hypothetical concept used in physics to represent a particle with a single, concentrated electrical charge. It has no physical dimensions and is considered to be infinitesimally small.

How do you calculate the electric field of a point charge?

The electric field of a point charge can be calculated using the formula E = kq/r^2, where k is the Coulomb's constant, q is the charge of the point charge, and r is the distance from the point charge to the point where the electric field is being measured.

What is the difference between a positive and negative point charge?

A positive point charge has a surplus of protons and an overall positive charge, while a negative point charge has a surplus of electrons and an overall negative charge. In terms of electric fields, a positive point charge will have electric field lines pointing away from it, while a negative point charge will have electric field lines pointing towards it.

What is the superposition principle in relation to point charges?

The superposition principle states that the total electric field at any point in space is the vector sum of the individual electric fields created by each point charge. This allows for the simplification of complex charge distributions into simpler point charges for calculation purposes.

How do point charges interact with each other?

Point charges interact with each other through the electromagnetic force. Like charges repel each other, while opposite charges attract each other. The strength of this interaction is determined by the magnitude of the charges and the distance between them.

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