- #1
Two Point Charges: Physics Problem Help
- Thread starter phunphysics2
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SUMMARY
The discussion focuses on solving a physics problem involving two point charges, qA and qB, and their interaction with a test charge. The correct approach involves using the electric field formula E = k[q]/r², rather than Coulomb's law, to determine the zero-field point. Participants emphasize the importance of visualizing the charge arrangement and applying the cross-multiplication method to solve for the distance x from the test charge to qB. The conversation highlights the necessity of understanding the relationship between the charges and their distances to accurately solve the problem.
PREREQUISITES- Understanding of electric fields and Coulomb's law
- Familiarity with the formula E = k[q]/r²
- Basic algebra skills, particularly cross-multiplication
- Ability to visualize charge arrangements in physics problems
- Study the application of the electric field formula E = k[q]/r² in various scenarios
- Practice problems involving multiple point charges and their interactions
- Learn about the concept of zero-field points in electric fields
- Explore graphical methods for visualizing electric fields and charge distributions
Students studying physics, particularly those focusing on electromagnetism, as well as educators seeking to enhance their teaching methods for electric field concepts.
- #2
gneill
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From the second attachment (the one on the right) it looks as though you need only cross multiply and solve for x to finish.
- #3
phunphysics2
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I don't know how to do so mathematically...
- #4
rude man
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Your starting formula is wrong.
Draw a picture of the two charges along a line, then equate Coulomb attraction of a unit (positive) test charge to qB to repulsion of that test charge from qA.
Hint: the zero-field point might be between qA and qB, or it might not ...
Draw a picture of the two charges along a line, then equate Coulomb attraction of a unit (positive) test charge to qB to repulsion of that test charge from qA.
Hint: the zero-field point might be between qA and qB, or it might not ...
- #5
phunphysics2
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Coulomb's law is not used. My professor said to only use the E=k[q]/rsquared formula...
- #6
phunphysics2
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I know that the order of the point charges goes as followed
qb -------------------qa--------------------P
qb -------------------qa--------------------P
- #7
rude man
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phunphysics2 said:
Never mind, you called x the distance from p to qB and d the distance between qA and qB, so what you wrote is fine.
- #8
gneill
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phunphysics2 said:
Really?
If ##\frac{a}{b} = \frac{c}{d}## then ##a \cdot d = b \cdot c##
You've never seen this?
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