What is the net electric field at point P in this physics problem?

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Homework Help Overview

The discussion revolves around calculating the net electric field at a specific point P due to two point charges, Q1 and Q2, which are positioned 3 meters apart. The charges are given as Q1 = 14 C and Q2 = +20 C, with point P located 2 meters to the right of Q2.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to calculate the electric field contributions from both charges at point P, providing numerical values for each. Some participants question the sign of Q1's charge and the importance of including units and direction in the final answer.

Discussion Status

The discussion is ongoing, with participants providing feedback on the calculations and emphasizing the need for clarity regarding the direction of the electric field. There is an acknowledgment of the large values obtained due to the nature of the charges involved.

Contextual Notes

Participants are discussing the implications of charge signs and the vector nature of electric fields, highlighting the importance of including both magnitude and direction in the final answer.

Burger
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Physics Problem , please help I'm writing a test tomorrow and want to know if I'm right.
The Question :

Two point charges Q1 and Q2 are spaced 3m apart.

Q1's charge = 14C
Q2's charge = +20 C

*Q1 -------(3meters)------- *Q2 ----(2meters)---- *P

Calculate the net electric field at point P, 2m right from where Q2 is situated?


My Calculations :

Q1 on P = -5.04 x10^9
Q2 on P = 4.5 x10^10

Final answer = Net : 3.996x10^10


Formula used:

E = (k*Q)/r^2
 
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Hello, Burger. Welcome to PF!

Did you forget to include the sign of Q1 when you stated Q1 = 14 C?

It is important to always include units with your answers.

Just to be sure that you have a full understanding, what is the interpretation of the negative sign for your answer for the electric field of Q1 at P?

Finally, electric field is a vector. So, it has a magnitude and a direction. Therefore, your final answer for the field at P should include both a magnitude and a direction. The direction should be clearly stated and not left to the reader to interpret.

Otherwise, your numbers look good! (You're getting a very large answer because a Coulomb is a huge amount of static charge.)
 
Q1's charge = -14 C

Thanks for the help! Will ace the Test hopefully. I must just remember to include the direction the N•C^-1
 
OK. Good luck with the test!
 

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