Question

If you know that the Solar intensity at Earth is S​0​ = 1361 W/m2​ ​, what is the Electric field strength of Solar radiation at Pluto? (you need to know the Sun to Earth distance

a​E​ =1.5x101​ 1​mandtheSuntoPlutodistancea​P​ =5.9x101​ 2​ m)

Answer 1

We know that:

Intensity = Power/Area = P/(4*pi*R^2)

Since Power of solar radiation will remain constant, So

Intensity is inversely proportional to the square of distance from Source (Sun)

So,

I2/I1 = (R1/R2)^2

I2 = Intenisty of solar radiation at Pluto = I1*(R1/R2)^2

I2 = 1361*[(1.50*10^11)/(5.9*10^12)]^2

I2 = 0.8797 W/m^2 = 0.88 W/m^2

Now relation between Electric field strength and Intensity is given by:

I2 = (1/2)*c*e0*E_max^2

E_max = sqrt (2*I/(c*e0))

c = speed of light = 3*10^8 m/s

e0 = 8.854*10^-12

So,

E_max = sqrt (2*0.88/(3*10^8*8.854*10^-12))

E_max = 25.74 V/m

Let me know if you've any query.