Radiation pressure

Definition

Radiation pressure is the pressure exerted by electromagnetic radiation on any surface due to the transfer of momentum from the photons to that surface. It is a key concept in understanding how light and other forms of electromagnetic waves can exert force.

5 Must Know Facts For Your Next Test

1. Radiation pressure can be calculated using $P = \frac{E}{c}$ for perfectly absorbing surfaces, where $P$ is the radiation pressure, $E$ is the energy flux, and $c$ is the speed of light.
2. For perfectly reflecting surfaces, the radiation pressure doubles to $P = \frac{2E}{c}$ because photons impart double their momentum during reflection.
3. Radiation pressure plays a crucial role in astrophysics, such as in the balance of forces within stars and the formation of solar winds.
4. A laser beam can exert noticeable radiation pressure due to its high intensity and focused energy flux.
5. In space exploration, concepts like solar sails utilize radiation pressure for propulsion without fuel.

Review Questions

• How does radiation pressure differ between perfectly absorbing and perfectly reflecting surfaces?
• Why is radiation pressure significant in astrophysical phenomena?
• What practical applications make use of radiation pressure?

Related terms

Photon: A quantum of electromagnetic energy that carries momentum and exerts force when interacting with matter.

Electromagnetic Wave: Oscillating electric and magnetic fields that propagate through space carrying energy and momentum.

Solar Sail: A spacecraft propulsion method that uses large reflective surfaces to harness radiation pressure from sunlight for movement.