Electric Field direction question

In summary, at a certain spot with an electric field of 280000N/C pointing due south, the magnitude and direction of force on a charge of -4.0*10^-6C would be 1.12N pointing north. The direction of the force is determined by the charge of the particle, with positive charges moving in the same direction as the electric field, and negative charges moving in the opposite direction. When an electron moves at constant velocity, there is no net force acting on it, thus the electric field at that point would be 0. Therefore, the voltage at that point would also be 0.
  • #1
Suy
101
0

Homework Statement


An electric field of 280000N/C points due south at a certain spot. what are the magnitude and direction of the force that acts on a charge of -4.0*10^-6C at this spot?

Homework Equations


The Attempt at a Solution


I don't know how to get the direction, is it south? please explain it...ty
And for question like this, what assumption would you make?, because i don't know the source charge is negative or positive
 
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  • #2
Suy said:
I don't know how to get the direction, is it south? please explain it...ty
And for question like this, what assumption would you make?, because i don't know the source charge is negative or positive
By convention, the electric field direction is the direction that a positive charge will move when placed in the field.

AM
 
  • #3
The answer for this question would be north?
ty
 
  • #4
Suy said:
The answer for this question would be north?
ty
What is the expression for the force,
[tex]\vec F[/tex],
on charge q when placed in a field
[tex]\vec E[/tex] ?

AM
 
  • #5
I know how to get the force, but i am not sure how to get the direction,
if the electric field direction is the direction that a positive charge will move,
electric field due south, the source charge would negative and the placed charge is negative , repel, it would north?
Please confirm if i am right ty...
btw, when an electron moving at constant velocity, from negative to positive plate(parallel), What is the voltage?
because F=Fe F=ma Fe=Eq
a=om/s2 Fe=0 0=Eq E=0N/C E=V/d V=0V
am i right?
 
  • #6
Suy said:
I know how to get the force, but i am not sure how to get the direction,
if the electric field direction is the direction that a positive charge will move,
electric field due south, the source charge would negative and the placed charge is negative , repel, it would north?
Please confirm if i am right ty...
btw, when an electron moving at constant velocity, from negative to positive plate(parallel), What is the voltage?
because F=Fe F=ma Fe=Eq
a=om/s2 Fe=0 0=Eq E=0N/C E=V/d V=0V
am i right?
I am trying to get you to solve this. You can do it. If the electric field direction is south, which is the direction of the force on a positive charge placed in that field, then what is the direction of the force on a negative charge placed in that field?

If an electron moves at constant velocity, is there a net force acting on it? From that answer, what can you say about the electric field? Since E = V/d what can you say about V?

AM
 
  • #7
Andrew Mason said:
I am trying to get you to solve this. You can do it. If the electric field direction is south, which is the direction of the force on a positive charge placed in that field, then what is the direction of the force on a negative charge placed in that field?

If an electron moves at constant velocity, is there a net force acting on it? From that answer, what can you say about the electric field? Since E = V/d what can you say about V?

AM

But i understand what you mean, it would go north and repel,because if the positive charge placed in that field, and due south(toward the source charge), the source charge will be negative because of attraction,but for the question the negative was placed there, so it would repel and to the north,
but are you trying to tell me actually the direction of negative charge is south? If it is , please tell me what am i wrong?

constant velocity ,acceleration is 0, no force is acting on it, there will be no electric field
V=0
 
  • #8
Suy said:
But i understand what you mean, it would go north and repel,because if the positive charge placed in that field, and due south(toward the source charge), the source charge will be negative because of attraction,but for the question the negative was placed there, so it would repel and to the north,
but are you trying to tell me actually the direction of negative charge is south? If it is , please tell me what am i wrong?
Your answer is right but you are struggling with the explanation. It is very simple. The force vector is given by:

[tex]\vec F = q\vec E[/tex]

If q is positive, how does the direction of the electric force F compare to the direction of the electric field E? If q is negative, what is the direction of F compared to E?

constant velocity ,acceleration is 0, no force is acting on it, there will be no electric field
V=0
Correct.

AM
 

1. What is an electric field direction?

The electric field direction is the direction in which a positive test charge would move if placed in an electric field. It is represented by lines called electric field lines that show the direction of the force acting on a positive test charge at different points in the field.

2. How is the direction of an electric field determined?

The direction of an electric field is determined by the direction of the electric force acting on a positive test charge. The electric force is always in the direction of the field lines, which radiate outward from positive charges and inward toward negative charges.

3. Can the direction of an electric field change?

Yes, the direction of an electric field can change depending on the distribution of charges in the surrounding space. If there are multiple charges present, the electric field direction will be the vector sum of the individual electric fields due to each charge.

4. How does the direction of an electric field affect the motion of a charged particle?

The direction of the electric field determines the direction of the electric force acting on a charged particle. If the electric field and electric force are in the same direction, the particle will accelerate in the direction of the field. If they are in opposite directions, the particle will decelerate or change direction.

5. Can the direction of an electric field be negative?

No, the direction of an electric field is always positive. However, the strength of the electric field can be negative if the field is pointing in the opposite direction of the force acting on a positive test charge. This occurs when the field is created by a negative charge.

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