Is the Unit Vector Always in the Direction from the Charge to the Point?

In summary, The conversation includes a student struggling with a practice exam problem and receiving help from a teacher. The student's answer and work were correct, but they could have used a symmetry argument to save effort. The student misinterpreted the instructions but eventually got the correct answer. They also had a question about the unit vector R in the equation for the electric field at point P due to charge Q, which was clarified by the teacher.
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  • #2
Your answer and work look OK to me.
 
  • #3
Thx, my confidence doesn't feel so shattered now :P
 
  • #4
Though your work was just fine, you could save yourself some effort by using a symmetry argument.
 
  • #5
Teacher just got back to me... turns the side of the square is A...somehow looking at how they depicted A in that drawing made me think A was the distance from center... even though it says in the instructions that A is the whole side... zzz

using distance from center = a/2 then problem comes out to their answer 3.05e13
 
  • #6
D'oh! Sorry about that... I must have been sleeping also. (I just looked at the diagram and ASSumed that "a" was the distance from the origin.) :frown:
 
  • #7
It's ok...this problem was booby trapped! :cry:
 
  • #8
o quick question...

is the unit vector R always in direction from the charge to the point..QP
 
  • #9
FocusedWolf said:
is the unit vector R always in direction from the charge to the point..QP
Yes, if you mean in the expression for the field at point P due to charge Q:
[tex]\vec{E} = \frac{k Q}{R^2} \hat{R}[/tex]
 

FAQ: Is the Unit Vector Always in the Direction from the Charge to the Point?

What is an electric field?

An electric field is a region in which an electrically charged particle experiences a force. It is created by other charged particles and can be either attractive or repulsive.

How is the electric field at a point measured?

The electric field at a point is measured by the force exerted on a unit positive charge placed at that point. This is known as the electric field strength or electric field intensity.

What factors affect the strength of the electric field at a point?

The strength of the electric field at a point is affected by the magnitude and direction of the charge that creates the field, as well as the distance between that charge and the point in question. It also depends on the medium in which the electric field exists.

How is the direction of the electric field at a point determined?

The direction of the electric field at a point is determined by the direction in which a positive test charge would move if placed at that point. It is always in the direction of the force exerted on a positive test charge by the electric field.

What is the difference between electric potential and electric field at a point?

Electric potential is a measure of the potential energy a unit charge would have at a given point in an electric field. It is a scalar quantity, while electric field is a vector quantity that describes the force experienced by a charged particle at a given point in an electric field.

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