How do I check if it is a positive charge or negative charge?

Click For Summary

Homework Help Overview

The discussion revolves around determining the nature of a charge (positive or negative) based on the electric field contributions from multiple charges at a specific point. The context involves analyzing the electric field at the origin due to charges Q, q1, and q2, with a focus on the conditions under which the net electric field is zero.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants explore the relationship between the electric field components and the polarity of the charges involved. Questions arise regarding the necessity for the electric field contributions to cancel each other out, particularly focusing on the x-component due to charge Q and the corresponding effect of charge q1.

Discussion Status

The discussion is active, with participants questioning the assumptions about the polarity of the charges based on the requirement for the net electric field to be zero. Some guidance is offered regarding the relationship between the components of the electric field and the charges, but no consensus has been reached on the specific nature of the charges.

Contextual Notes

Participants note that the problem can also be approached by considering the y-components of the electric field, suggesting that multiple methods may lead to a deeper understanding of the situation.

CKaiL
Messages
38
Reaction score
1

Homework Statement


s5kahj.png


Homework Equations

The Attempt at a Solution


[/B]
The electric field at the origin O, due to charges Q, q1 and q2, is equal to zero
Hence , EQ = Eq1
q = cos30 x 300 x10^-9/4 * 1.8^2 = 210 x10^-9 C

So I am able to find out that q = 210 x 10^-9 C and that mean that B and C cannot be the answer which left me with A and D.

How do I check if it is a positive charge or negative charge?

 
Last edited by a moderator:
Physics news on Phys.org
CKaiL said:

Homework Statement


s5kahj.png


Homework Equations

The Attempt at a Solution



The electric field at the origin O, due to charges Q, q1 and q2, is equal to zero
Hence , EQ = Eq1
q = cos30 x 300 x10^-9/4 * 1.8^2 = 210 x10^-9 C

So I am able to find out that q = 210 x 10^-9 C and that mean that B and C cannot be the answer which left me with A and D.

How do I check if it is a positive charge or negative charge?
[/B]
The x component at the origin due to Q is what polarity? So the polarity of Ex due to q1 has to be the opposite, right? So what then does the polarity of q1 have to be?
 
Why does it has to be opposite for the polarity of Ex due to q1?
 
CKaiL said:
Why does it has to be opposite for the polarity of Ex due to q1?
because the net E field at the origin is zero so q1 has to cancel out the x component of Q.
 
What about the q2 at the y component?
 
CKaiL said:
What about the q2 at the y component?
q2 does not produce an x compnent of the E field at the origin. You are summing x components of E at the origin.

By the way, you can also solve this problem with summing y components of E = 0 at the origin. I suggest you do it for increased understanding.
 

Similar threads

Replies
13
Views
2K
Replies
5
Views
1K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 2 ·
Replies
2
Views
8K
Replies
23
Views
5K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K