## Related questions with answers

Radiant energy from the Sun arrives at Earth with an intensity of $1.5 kW/m^2.$ Making the rough approxima- Sion that all photons are absorbed, find (a) the radiation pressure and (b) the total force experienced by Earth due to this “solar wind.”

Solution

Verifieda) The total energy is by definition is the energy of a single photon times the number of photons emitted ($n$), equivalently, you can define it as the power ($W$) emitted in a given period of time. Starting with this definition and considering the variation in momentum $\Delta p$ in a certain time interval $\Delta t$, we could derive an expression for the pressure ($P$) that relate it to the problem given quantities.

$\begin{gather*} \therefore W \Delta t = nhf = \frac{nhc}{\Delta \lambda}\\ \because W = IA \:\:,\:\: \Delta \lambda = \frac{h}{\Delta p}\\ \therefore IA\Delta t = n\Delta pc \\ \because F_{\text{tot}} = n \frac{\Delta p }{\Delta t} \:\:,\:\: P = \frac{F_{\text{tot}}}{A} = \frac{n\Delta p }{A\Delta t} \\ \therefore P = \frac{I}{c} = \frac{1.5 \times 10^3\:\:\mathrm{W/m^2}}{3\times 10^8\:\:\mathrm{m/s}} \\ \boxed{\therefore P = \mathbf{5\times 10^{-6} \:\:Pa} } \end{gather*}$

## Create an account to view solutions

## Create an account to view solutions

## Recommended textbook solutions

#### Physics for Scientists and Engineers: A Strategic Approach with Modern Physics

4th Edition•ISBN: 9780133942651Randall D. Knight#### Mathematical Methods in the Physical Sciences

3rd Edition•ISBN: 9780471198260Mary L. Boas#### Modern Physics for Scientists and Engineers

2nd Edition•ISBN: 9780805303087 (1 more)Randy Harris#### Fundamentals of Physics

10th Edition•ISBN: 9781118230718 (1 more)David Halliday, Jearl Walker, Robert Resnick## More related questions

1/4

1/7