Determining the direction of electric field lines

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Discussion Overview

The discussion revolves around the determination of electric field lines in relation to positive and negative charges, focusing on their direction and characteristics. Participants explore concepts related to the magnitude of charges and the implications for the electric field lines' behavior.

Discussion Character

  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants state that electric field lines point away from positive charges and toward negative charges, questioning the implications of charge magnitudes.
  • One participant clarifies that "magnitude" refers to the absolute value of the charge, making the sign irrelevant to the discussion of magnitude.
  • There is a suggestion that the electric field lines are longer for one charge, with a proportional relationship to distance, raising questions about the relationship between distance and field line characteristics.
  • Another participant emphasizes that the electric field's strength is related to the distance between neighboring field lines rather than the length of the lines themselves.
  • One participant proposes a thought experiment involving varying magnitudes of charges to visualize the differences in field line characteristics.
  • A link to an interactive applet is provided to explore the behavior of electric field lines with different charge configurations.

Areas of Agreement / Disagreement

Participants express differing views on the implications of charge magnitudes and the characteristics of electric field lines, indicating that multiple competing perspectives remain unresolved.

Contextual Notes

There are limitations in the assumptions made regarding charge magnitudes and their effects on electric field lines, as well as the interpretation of distance in relation to field strength.

asilvester635
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In general, the field lines points away from the positive charge and toward the negative charge. The answer is letter E, but the second part of the answer says, "the magnitude of q1 is less than the magnitude of q2". Is that because q1 is negative and q2 is positive?

Electric field lines.jpeg
 

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asilvester635 said:
the magnitude of q1 is less than the magnitude of q2". Is that because q1 is negative and q2 is positive?
No. The word “magnitude” means “absolute value”, so the sign of the charge is irrelevant.

Besides the direction of the field lines, what else do you notice about them that is different between the two charges?
 
Dale said:
No. The word “magnitude” means “absolute value”, so the sign of the charge is irrelevant.

Besides the direction of the field lines, what else do you notice about them that is different between the two charges?
The electric field lines are longer for q1, and the magnitude is proportional to the distance. So the bigger the distance, the smaller the magnitude, as is the case with this sketch?
 
Several of the field lines from q2 go off the page to infinity, so those are the longest field lines. But that isn’t the distance of interest with field lines.

The E field is proportional to the distance between neighboring field lines, not the distance along a single field line. So look at the distance between field lines immediately surrounding each charge. What do you notice?
 
I do not follow your question. Still assume, q1 negative and q2 positive and their magnitudes are equal then what do you expect.what features the field lines should have. one is the direction of field lines what another feature is there about these lines. Try to draw or imagine lines for different cases from from |q1| = 0 to
|q1| = |q2|.
 
asilvester635 said:
The electric field lines are longer for q1, and the magnitude is proportional to the distance. So the bigger the distance, the smaller the magnitude, as is the case with this sketch?

Why don't you look at this applet?

https://phet.colorado.edu/sims/html/charges-and-fields/latest/charges-and-fields_en.html

First use one positive and one negative charge. Then try pilling on more of one charge, and then repeat by using the other charge. Figure out for yourself which scenario resembles that you were given in the figure.

Zz.
 

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