# Direction of electric field

## Homework Statement

a thin nonconducting rod is bent in a circular arc. Half is given a uniformly distributed postive charge and the other half uniformly negative. Draw the direction of the electric field at the center of the circle.

## Homework Equations

E=Fe/qo, F=qE E=ke(q/r2)r

## The Attempt at a Solution

Im not really sure what to apply here, a test particle is always postive, so if placed in the middle of the circle made by the bended rod it the electric field points to the negative side....

Gokul43201
Staff Emeritus
Gold Member
Im not really sure what to apply here, a test particle is always postive, so if placed in the middle of the circle made by the bended rod it the electric field points to the negative side....
That's correct. To make sure you've got this completely figured out try and draw the field lines everywhere (inside and ouside the ring).

Electric field lines are drawn propagating outwards from a positive charge and in towards a negative charge. Using this knowledge, what can you determine about the electric field at the center of the said ring? Use symmetry arguments.

## Homework Statement

a thin nonconducting rod is bent in a circular arc. Half is given a uniformly distributed postive charge and the other half uniformly negative. Draw the direction of the electric field at the center of the circle.

## Homework Equations

E=Fe/qo, F=qE E=ke(q/r2)r

## The Attempt at a Solution

Im not really sure what to apply here, a test particle is always postive, so if placed in the middle of the circle made by the bended rod it the electric field points to the negative side....

doesnt there need to be a charge in the middle in the first place to relate the electric field to..?

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The electric field is present regardless of whether or not a test charge is in place. The test charge serves the purpose of allowing one to manually probe the field and determine its strength at certain points.

doesnt there need to be a charge in the middle in the first place to relate the electric field to..?