Step 1:

(a)

Observe the figure:

The three point charges are , and .

The angle of the field at the dot from the top charge is .

The angle of the field at the dot from the bottom charge is .

The angle of the field at the dot from the top right charge is .

Electric field due to charged particle is , where

is the permittivity of free space .

is the charge of the electron.

is the distance between the two point charges.

Step 2:

The distance between the top charge and the dot is .

For the charged particle along bottom surface is .

The distance between the bottom charge and the dot is .

For the charged particle along bottom surface is .

The distance between the top left charge and the dot is .

For the charged particle along bottom surface is .

Step 3:

Find the net electric field.

is sum of horizontal and vertical components.

Find the sum of horizontal components.

Find the sum of vertical components.

Therefore .

Solution:

.

(b)

From (a): .

Find the magnitude of electric field strength.

Strength of the electric field is

(c)

From (a): .

Find the direction of electric field.

Direction of electric field is clockwise.