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Step 1:

Draw the related diagram:

The angle of the field at the dot from the upper left charge is .

The angle of the field at the dot from the lower left charge is .

The angle of the field at the dot from the lower 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 upper left charge and the point is .

For the charged particle along upper left surface is .

The distance between the lower left charge and the point is .

For the charged particle along lower left surface is .

The distance between the lower right charge and the point is .

For the charged particle along lower right surface is .

Step 3:

Find the net electric field.

is sum of horizontal and vertical components.

Find the sum of horizontal components.

.

Substitute and .

.

The horizontal component is .

Find the sum of vertical components.

.

Substitute and .

.

The vertical component is .

.

.

The electric field at point in component form is .

Therefore .

Find the magnitude of electric field strength.

Strength of the electric field is

Find the direction of electric field.

Direction of electric field is above the -axis.

Solution:

Strength of the electric field is

Direction of electric field is above the -axis.