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

Click For Summary
SUMMARY

The discussion focuses on determining the polarity of electric charges based on their contributions to the electric field at a specific point, the origin O. The calculations reveal that the charge q is 210 x 10^-9 C, leading to the conclusion that options B and C are eliminated, leaving A and D as potential answers. The polarity of charge q1 must be opposite to that of charge Q to ensure that the net electric field at the origin remains zero. Additionally, the discussion emphasizes the importance of considering both x and y components of the electric field for a comprehensive understanding.

PREREQUISITES
  • Understanding of electric fields and Coulomb's law
  • Familiarity with vector components in physics
  • Knowledge of charge polarity and its effects on electric fields
  • Basic algebra for solving equations involving electric charges
NEXT STEPS
  • Study the principles of electric field superposition
  • Learn about vector addition in electric fields
  • Explore the concept of charge polarity and its implications in electrostatics
  • Practice problems involving the calculation of electric fields from multiple point charges
USEFUL FOR

Students studying electromagnetism, physics educators, and anyone seeking to deepen their understanding of electric fields and charge interactions.

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

Potential difference in between positive and negative charge
  • · Replies 13 ·
Replies
13
Views
2K
Mechanisms Involved When Charging a Battery
  • · Replies 10 ·
Replies
10
Views
2K
Confusion on the distribution of charge
  • · Replies 7 ·
Replies
7
Views
2K
Capacitors, equipotentials, and electric fields
  • · Replies 5 ·
Replies
5
Views
1K
A positive charge of magnitude Q1 = 8.5 nC is located....
  • · Replies 2 ·
Replies
2
Views
8K
Electric field external to Conducting Hollow Sphere with charge inside
  • · Replies 23 ·
Replies
23
Views
4K
Gauss' Law question about a conducting rod
  • · Replies 3 ·
Replies
3
Views
2K
Finding the final speed of a Positive and Negative Charge
  • · Replies 5 ·
Replies
5
Views
2K
Maximum charge on the plates of a capacitor
  • · Replies 2 ·
Replies
2
Views
2K
Evaluate the electric field for two slabs of charge
  • · Replies 2 ·
Replies
2
Views
3K