**Calculation of Electric Field Intensity**

The electric field is acting vertically upwards on a small body of mass 1gm and charge -1muC. The body is projected with a velocity 10m/s at an angle of 45 degrees with the horizontal. Given that the horizontal range of the body is 2m, we need to calculate the intensity of the electric field.

**Formula to Calculate Electric Field Intensity**

The electric field intensity at a point is given by the formula E = F/q, where F is the force acting on the charge q.

**Calculation of Force on the Body**

The force acting on the body is given by the formula F = qE, where E is the electric field intensity.

The initial vertical velocity of the body is zero. Therefore, the only force acting on the body is the electric force.

Using the formula F = ma, we can write the equation of motion for the body as m(d^2y/dt^2) = qE.

Integrating this equation with respect to time, we get the vertical displacement of the body as y = (qE/m)t^2/2.

**Calculation of Horizontal Range**

The horizontal range of the body is given by the formula R = utcosθ, where u is the initial velocity of the body, θ is the angle of projection, and t is the time of flight.

The time of flight of the body can be calculated from the vertical displacement equation as t = sqrt(2y/m), where y is the maximum vertical displacement.

Substituting the value of t in the formula for horizontal range, we get R = 2m.

**Calculation of Electric Field Intensity**

Substituting the value of t in the vertical displacement equation, we get y = (qE/m)R^2/8.

Rearranging this equation, we get E = (8my)/(qR^2).

Substituting the given values, we get E = 4x10^3 N/C.

Therefore, the intensity of the electric field is 4x10^3 N/C.