Question

Like all light, the light from the sun is an electromagnetic wave. In the vicinity of Earth, the average intensity of sunlight is about 1400W/m^2. For this problem, assume that sunlight is a monochromatic plane wave, so you can apply the equations for the energy and pressure of an EM wave.

(a) What is the amplitude of the electric field at Earth?

(b) If I go outside on a sunny day, the magnetic field sensor on my phone tells me the magnitude of the magnetic field is around 40µT. What fraction of this field is due to the light from the sun?

(c) A solar sail is a proposed method of propulsion in space that uses a large, thin, sheet of reflective material (a ”sail”). The radiation pressure from the sun will accelerate the sail. If the sail has an area of 1200m^2 calculate the average force on the sail when it is at Earth?

(d) If the sail has a mass of 32kg, what is the acceleration of the sail? How far does it have to travel before reaches a speed of 340m/s? Assume the force is constant. Express your answer in millions of kilometers

Answer 1