# Solar Powered Spaceship

**Electricity and Magnetism**Level 4

*all*of the sun's radiation comes out at this wavelength. If we think about the radiation as photons, each photon carries a momentum given by \(p=h/\lambda\) and an energy \(E=hc/\lambda\) by quantum mechanics.

One can use the electromagnetic radiation to propel spaceships, although it doesn't work all that well even though it is cheap. Consider a spaceship propelled by a "solar sail", a perfectly square reflecting sheet of material 1 km on a side oriented so the normal points directly towards the sun. At the earth's orbit, how much force **in Newtons** would such a solar sail experience?

**Details and Assumptions**

- The earth orbits at a distance of roughly \(1.5 \times 10^8\) km from the sun.
- The speed of light is \(3 \times 10^8\) m/s.
- Planck's constant is \(h=6.63\times 10^{-34}\text{ kg}\cdot\text{m}^2\text{/s}\).