Electric field due to point charge

[th3plan]

Homework Statement

Two particles are fixed to an x axis: particle 1 charge -2.00x10^-7 at x=6.0cm and particle 2 at 2.00x10^-7 C at x=21.0cm. Midway between the particles, what is there net electric field?

Homework Equations

E=kq/r^2

The Attempt at a Solution

Ok so I drew the picture out, and i know q1 is negative so the electrive field is going towards it to the left, and q2 is + so that means the field is going to the left toward q1, so that means Enet= -E1-E2 , and its negative because there both going to the left? Am i correct on this ? I know the rest of problem is just plugging in numbers, but whant to make sure I am correct on theory. Also let's say that q1 was postive does that mean q1 would go to the left, and q2 field would go to the right, resulting in a zero net force ?

 

[LowlyPion]

Homework Statement

Two particles are fixed to an x axis: particle 1 charge -2.00x10^-7 at x=6.0cm and particle 2 at 2.00x10^-7 C at x=21.0cm. Midway between the particles, what is there net electric field?

Homework Equations

E=kq/r^2

The Attempt at a Solution

Ok so I drew the picture out, and i know q1 is negative so the electrive field is going towards it to the left, and q2 is + so that means the field is going to the left toward q1, so that means Enet= -E1-E2 , and its negative because there both going to the left? Am i correct on this ? I know the rest of problem is just plugging in numbers, but whant to make sure I am correct on theory. Also let's say that q1 was postive does that mean q1 would go to the left, and q2 field would go to the right, resulting in a zero net force ?

I'd say you have grasped the concepts. The E field of 0 in your follow up is however only at the mid point which I'm sure you already understand.

 

[baba89]

Yes, you are correct in your understanding of the theory. The electric field due to a point charge is always directed away from positive charges and towards negative charges. In this case, since both charges are of opposite signs, the electric fields will point in opposite directions and the net electric field at the midpoint will be the sum of the two individual electric fields, with the negative sign indicating the direction.

If q1 was positive, then the direction of the electric field would be reversed, with the field pointing away from q1 and towards q2. In this case, the net electric field at the midpoint would be zero, since the two fields would cancel each other out.