1. What is Radiation Pressure?

Radiation pressure is the pressure exerted upon any surface exposed to electromagnetic radiation. It results from the momentum transfer of photons to the surface they strike.

2. How Does the Calculator Work?

The calculator uses the radiation pressure equation:

Where:

• \( p \) — Radiation pressure (Pascals)
• \( i \) — Intensity of radiation (W/m²)
• \( c \) — Speed of light (m/s)

Explanation: The equation shows that radiation pressure is directly proportional to the intensity of the radiation and inversely proportional to the speed of light.

3. Importance of Radiation Pressure

Details: Radiation pressure is important in astrophysics (e.g., stellar dynamics), laser applications, and the design of solar sails for spacecraft propulsion.

4. Using the Calculator

Tips: Enter intensity in W/m² and speed of light in m/s (default is 299792458 m/s). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical value for radiation pressure from sunlight?
A: At Earth's distance from the Sun, solar radiation pressure is about 4.56 μPa (microPascals).

Q2: Why is the speed of light in the denominator?
A: The pressure depends on photon momentum (p=E/c), and intensity is power per area (E/t·A), so pressure = (E/c)/(t·A) = i/c.

Q3: When does this simple formula not apply?
A: For surfaces that aren't perfectly absorbing (need to account for reflection) or at relativistic velocities.

Q4: How does radiation pressure relate to solar sails?
A: Solar sails use radiation pressure for propulsion - photons transfer momentum to the sail, creating a small but continuous force.

Q5: Can radiation pressure be significant on Earth?
A: Only with extremely intense light sources like powerful lasers - sunlight pressure is too weak to notice in everyday situations.