Solving an Electric Field Problem: Magnitude & Direction of Force on a Charge

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Homework Help Overview

The problem involves calculating the force acting on a charge in an electric field, specifically focusing on the magnitude and direction of that force given an electric field strength and a negative charge value.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the calculation of force using the equation F = qE and question the implications of the negative charge on the direction of the force. There is also a consideration of whether the negative sign should be included in the final answer.

Discussion Status

The discussion is exploring the interpretation of the negative sign in relation to the direction of the force. Some participants affirm the calculation while others clarify the significance of the sign in vector representation, indicating a productive exchange of ideas without a clear consensus.

Contextual Notes

Participants are navigating the nuances of vector directionality and the implications of charge sign in the context of electric fields. There is a mention of potential discrepancies with textbook definitions or interpretations.

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Homework Statement



An electric field of 281,000 N/C points due west at a certain point. What are the magnitude and direction of the force that acts on a charge of -7.4 µC at this spot?

Homework Equations





The Attempt at a Solution



I just took (-7.4*10^-6)*281000

...to get -2.0794 N, and that seems incorrect.

please help me with this.
 
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The answer you have is correct because the Force is given by:

[tex] F = qE[/tex]

which is exactly what you did. Does your textbook [or whatever] say something else? Because there is no calculation error either [http://tinyurl.com/35fzsu].

Also, as you've got a (-) sign, the direction of the force will be opposite to that of the field i.e. due east.
 
oh, that's what it was. The negative sign. That is not supposed to be there, apparently.

thankyou.
 
rcmango said:
oh, that's what it was. The negative sign. That is not supposed to be there, apparently.

Actually, the sign is supposed to be there [or not be there]. Basically, it depends on what we are talking about. When we are concerned with a vector, we talk about it's magnitude and direction. If you were asked purely the magnitude, it is always greater than 0 i.e. +ive. But, the (-) sign indicates the direction. If I say that the force is -10N due west, it means that the force was 10N due east.
 

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