The energy flow to the earth from sunlight is about 1.40 kw/m2. part a find the maximum value of the electric field for a sinusoidal wave of this intensity.

Energy, E = Sqrt{Energy intensity*Speed of light*Magnetic constant}

Where,

Energy intensity = 1.40 kW/m^2 = 1400 W/m^2

Speed of light = 3*10^8 m/s

Magnetic constant = 4pi*10^-7 H

Therefore,

E = Sqrt{1400*3*10^8*4*pi*10^-7} = 726.49 v/m

Now,

Emax = E*sqrt (2) = 726.49*Sqrt (2) = 1027.41 v/m