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ere is a link to the image for both problems.

In the figure, two curved plastic rods form a circle of radius R in the standard x-y plane.

The charges of the rods are +q and -q on the rods. The charges are distributed uniformly.

What is the magnitude of the electric field at the center of the circle?

A k (4q / (pi R2))

B k (q2 / (2 pi R))

C k (2q / (pi R))

D k (q2 / (pi R2))

E 0

**I believe it is 0 because the charge is distributed uniformly across the surface of the field.**

In the figure, two curved plastic rods form a circle of radius R in the standard x-y plane.

The charges of the rods are +q and -q on the rods. The charges are distributed uniformly.

What is the direction of the electric field at the center of the circle?

A down (-y)

B up (+y)

C left (-x)

D right (+x)

E 0

**Since the top half is the + rod and the bottom half is the - rod I believe it would travel down because the field travels from + to -.**

The units of electric field are

A J / C

B J / (C m)

C J / m

D J C

E J m / C

**I thought the units of electric field were N/C. Am I overlooking something?**

Electric field lines enter charge B while electric field lines exit charge A. The number of

lines entering B equals the number of lines exiting A. The charges A and B are separated

from each other by a distance R. Therefore

A A is positive and B is negative

B A is negative and B is positive

C The magnitude of the electric field is the same everywhere

D The electric field is strongest midway between A and B

E A and B must have the same sign

**I believe it is A. A is positive and B is negative because field lines point away from positive charges and toward negative charges.**

Let me know if I'm on the right track.